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Sunday, January 27, 2019

Science and inventions of Leonardo da Vinci

From Wikipedia, the free encyclopedia

Leonardo Da Vinci
Da Vinci Vitruve Luc Viatour.jpg
Born
Leonardo Da Vinci

April 15, 1452 Vinci, Italy
DiedMay 2, 1519 (aged 67)
NationalityItalian
Known forPolymath: painter, sculptor, architect, musician, scientist, mathematician, engineer, inventor, anatomist, geologist, cartographer, botanist and writer
Notable work
Paintings including the Mona Lisa and The Last Supper. Many scientific drawings including The Vitruvian Man.
MovementHigh Renaissance

Leonardo da Vinci (1452–1519) was an Italian polymath, regarded as the epitome of the "Renaissance Man", displaying skills in numerous diverse areas of study. Whilst most famous for his paintings such as the Mona Lisa and the Last Supper, Leonardo is also renowned in the fields of civil engineering, chemistry, geology, geometry, hydrodynamics, mathematics, mechanical engineering, optics, physics, pyrotechnics, and zoology.

While the full extent of his scientific studies has only become recognized in the last 150 years, he was, during his lifetime, employed for his engineering and skill of invention. Many of his designs, such as the movable dikes to protect Venice from invasion, proved too costly or impractical. Some of his smaller inventions entered the world of manufacturing unheralded. As an engineer, Leonardo conceived ideas vastly ahead of his own time, conceptually inventing the parachute, an improved version of the helicopter, an armored fighting vehicle, the use of concentrated solar power, a calculator, a rudimentary theory of plate tectonics and the double hull. In practice, he greatly advanced the state of knowledge in the fields of anatomy, astronomy, civil engineering, optics, and the study of water (hydrodynamics).

Leonardo's most famous drawing, the Vitruvian Man, is a study of the proportions of the human body, linking art and science in a single work that has come to represent Renaissance Humanism.

Condensed biography

The Arno Valley

Leonardo da Vinci (April 15, 1452 – May 2, 1519) was born the illegitimate son of Messer Piero, a notary, and Caterina, a peasant woman. His early life was spent in the region of Vinci, in the valley of the Arno River near Florence, firstly with his mother and in later childhood in the household of his father, grandfather and uncle Francesco. 

His curiosity and interest in scientific observation were stimulated by his uncle Francesco, while his grandfather's keeping of journals set an example which he was to follow for most of his life, diligently recording in his own journals both the events of the day, his visual observations, his plans and his projects. The journals of Leonardo contain matters as mundane as grocery lists and as remarkable as diagrams for the construction of a flying machine. 

In 1466, Leonardo was sent to Florence to the workshop of the artist Verrocchio, in order to learn the skills of an artist. At the workshop, as well as painting and drawing, he learnt the study of topographical anatomy. He was also exposed to a very wide range of technical skills such as drafting, set construction, plasterworking, paint chemistry, and metallurgy

From Leonardo's journals - studies of an old man and the action of water.
 
Among the older artists whose work stimulated Leonardo's scientific interest was Piero della Francesca, then a man in his 60s, who was one of the earliest artists to systematically employ linear perspective in his paintings, and who had a greater understanding of the science of light than any other artist of his date. While Leonardo's teacher, Verrocchio, largely ignored Piero's scientifically disciplined approach to painting, Leonardo and Domenico Ghirlandaio, who also worked at Verrocchio's workshop, did not. Two of Leonardo's earliest paintings, both scenes of the Annunciation show his competent understanding of the linear perspective. 

Leonardo da Vinci was profoundly observant of nature, his curiosity having been stimulated in early childhood by his discovery of a deep cave in the mountains and his intense desire to know what lay inside. His earliest dated drawing, 1473, is of the valley of the Arno River, where he lived. It displays some of the many scientific interests that were to obsess him all his life, in particular geology and hydrology. 

Approach to scientific investigation

Studies of a fetus from Leonardo's journals
 
Investigating the motion of the arm.
 
During the Renaissance, the study of art and science was not perceived as mutually exclusive; on the contrary, the one was seen as informing upon the other. Although Leonardo's training was primarily as an artist, it was largely through his scientific approach to the art of painting, and his development of a style that coupled his scientific knowledge with his unique ability to render what he saw that created the outstanding masterpieces of art for which he is famous.

As a scientist, Leonardo had no formal education in Latin and mathematics and did not attend a university. Because of these factors, his scientific studies were largely ignored by other scholars. Leonardo's approach to science was one of intense observation and detailed recording, his tools of investigation being almost exclusively his eyes. His journals give insight into his investigative processes. 

A recent and exhaustive analysis of Leonardo as a scientist by Fritjof Capra argues that Leonardo was a fundamentally different kind of scientist from Galileo, Newton, and other scientists who followed him, his theorizing and hypothesizing integrating the arts and particularly painting. Capra sees Leonardo's unique integrated, holistic views of science as making him a forerunner of modern systems theory and complexity schools of thought.

Leonardo's notes and journals

Leonardo kept a series of journals in which he wrote almost daily, as well as separate notes and sheets of observations, comments and plans. He wrote and drew with his left hand, and most of his writing is in mirror script, which makes it difficult to read. Much has survived to illustrate Leonardo's studies, discoveries and inventions.

On his death, his writings were left mainly to his pupil Melzi with the apparent intention that his scientific work should be published. This did not take place in Melzi's lifetime, and the writings were eventually bound in different forms and dispersed. Some of his works were published as a Treatise on Painting 165 years after his death.

Publication

Leonardo illustrated a book on mathematical proportion in art written by his friend Luca Pacioli and called De divina proportione, published in 1509. He was also preparing a major treatise on his scientific observations and mechanical inventions. It was to be divided into a number of sections or "Books", Leonardo leaving some instructions as to how they were to be ordered. Many sections of it appear in his notebooks. 

These pages deal with scientific subjects generally but also specifically as they touch upon the creation of artworks. In relating to art, this is not science that is dependent upon experimentation or the testing of theories. It deals with detailed observation, particularly the observation of the natural world, and includes a great deal about the visual effects of light on different natural substances such as foliage.

Leonardo wrote:
Begun at Florence, in the house of Piero di Braccio Martelli, on the 22nd day of March 1508. And this is to be a collection without order, taken from many papers which I have copied here, hoping to arrange them later each in its place, according to the subjects of which they may treat. But I believe that before I am at the end of this [task] I shall have to repeat the same things several times; for which, O reader! do not blame me, for the subjects are many and memory cannot retain them [all] and say: ‘I will not write this because I wrote it before.’ And if I wished to avoid falling into this fault, it would be necessary in every case when I wanted to copy [a passage] that, not to repeat myself, I should read over all that had gone before; and all the more since the intervals are long between one time of writing and the next.

Natural science

Study of the graduations of light and shade on a sphere (chiaroscuro).

Light

Leonardo wrote:
The lights which may illuminate opaque bodies are of 4 kinds. These are; diffused light as that of the atmosphere; And Direct, as that of the sun; The third is Reflected light; and there is a 4th which is that which passes through [translucent] bodies, as linen or paper etc.

For an artist working in the 15th century, some study of the nature of light was essential. It was by the effective painting of light falling on a surface that modelling, or a three-dimensional appearance was to be achieved in a two-dimensional medium. It was also well understood by artists like Leonardo's teacher, Verrocchio, that an appearance of space and distance could be achieved in a background landscape by painting in tones that were less in contrast and colors that were less bright than in the foreground of the painting. The effects of light on solids were achieved by trial and error, since few artists except Piero della Francesca actually had accurate scientific knowledge of the subject.

At the time when Leonardo commenced painting, it was unusual for figures to be painted with extreme contrast of light and shade. Faces, in particular, were shadowed in a manner that was bland and maintained all the features and contours clearly visible. Leonardo broke with this. In the painting generally titled The Lady with an Ermine (about 1483) he sets the figure diagonally to the picture space and turns her head so that her face is almost parallel to her nearer shoulder. The back of her head and the further shoulder are deeply shadowed. Around the ovoid solid of her head and across her breast and hand the light is diffused in such a way that the distance and position of the light in relation to the figure can be calculated.

Leonardo's treatment of light in paintings such as The Virgin of the Rocks and the Mona Lisa was to change forever the way in which artists perceived light and used it in their paintings. Of all Leonardo's scientific legacies, this is probably the one that had the most immediate and noticeable effect.

Human anatomy

Leonardo wrote:
...to obtain a true and perfect knowledge ... I have dissected more than ten human bodies, destroying all the other members, and removing the very minutest particles of the flesh by which these veins are surrounded, ... and as one single body would not last so long, since it was necessary to proceed with several bodies by degrees, until I came to an end and had a complete knowledge; this I repeated twice, to learn the differences...
Study of the proportions of the head.

Topographic anatomy

Leonardo began the formal study of the topographical anatomy of the human body when apprenticed to Andrea del Verrocchio. As a student he would have been taught to draw the human body from life, to memorize the muscles, tendons and visible subcutaneous structure and to familiarize himself with the mechanics of the various parts of the skeletal and muscular structure. It was common workshop practice to have plaster casts of parts of the human anatomy available for students to study and draw. 

Two anatomical studies
 
If, as is thought to be the case, Leonardo painted the torso and arms of Christ in The Baptism of Christ on which he famously collaborated with his master Verrocchio, then his understanding of topographical anatomy had surpassed that of his master at an early age as can be seen by a comparison of the arms of Christ with those of John the Baptist in the same painting. 

In the 1490s he wrote about demonstrating muscles and sinews to students:
Remember that to be certain of the point of origin of any muscle, you must pull the sinew from which the muscle springs in such a way as to see that muscle move, and where it is attached to the ligaments of the bones.
His continued investigations in this field occupied many pages of notes, each dealing systematically with a particular aspect of anatomy. It appears that the notes were intended for publication, a task entrusted on his death to his pupil Melzi. 

In conjunction with studies of aspects of the body are drawings of faces displaying different emotions and many drawings of people suffering facial deformity, either congenital or through illness. Some of these drawings, generally referred to as "caricatures", on analysis of the skeletal proportions, appear to be based on anatomical studies.

Dissection

Dissection of the skull.

As Leonardo became successful as an artist, he was given permission to dissect human corpses at the hospital Santa Maria Nuova in Florence. Later he dissected in Milan at the hospital Maggiore and in Rome at the hospital Santo Spirito (the first mainland Italian hospital). From 1510 to 1511 he collaborated in his studies with the doctor Marcantonio della Torre.
I have removed the skin from a man who was so shrunk by illness that the muscles were worn down and remained in a state like thin membrane, in such a way that the sinews instead of merging in muscles ended in wide membrane; and where the bones were covered by the skin they had very little over their natural size.
In 30 years, Leonardo dissected 30 male and female corpses of different ages. Together with Marcantonio, he prepared to publish a theoretical work on anatomy and made more than 200 drawings. However, his book was published only in 1680 (161 years after his death) under the heading Treatise on painting

The organs of a woman's body.

Among the detailed images that Leonardo drew are many studies of the human skeleton. He was the first to describe the double S form of the backbone. He also studied the inclination of pelvis and sacrum and stressed that sacrum was not uniform, but composed of five fused vertebrae. He also studied the anatomy of the human foot and its connection to the leg, and from these studies, he was able to further his studies in biomechanics. 

Leonardo was a physiologist as well as an anatomist, studying the function of the human body as well as examining and recording its structure. He dissected and drew the human skull and cross-sections of the brain, transversal, sagittal, and frontal. These drawings may be linked to a search for the sensus communis, the locus of the human senses, which, by Medieval tradition, was located at the exact physical center of the skull. 

Leonardo studied internal organs, being the first to draw the human appendix and the lungs, mesentery, urinary tract, reproductive organs, the muscles of the cervix and a detailed cross-section of coitus. He was one of the first to draw a scientific representation of the fetus in the intrautero. 

Leonardo studied the vascular system and drew a dissected heart in detail. He correctly worked out how heart valves ebb the flow of blood yet he did not fully understand circulation as he believed that blood was pumped to the muscles where it was consumed. In 2005 a UK heart surgeon, Francis Wells, from Papworth Hospital Cambridge, pioneered repair to damaged hearts, using Leonardo's depiction of the opening phase of the mitral valve to operate without changing its diameter allowing an individual to recover more quickly. Wells said "Leonardo had a depth of appreciation of the anatomy and physiology of the body - its structure and function - that perhaps has been overlooked by some."

Leonardo's observational acumen, drawing skill, and the clarity of depiction of bone structures reveal him at his finest as an anatomist. However, his depiction of the internal soft tissues of the body are incorrect in many ways, showing that he maintained concepts of anatomy and functioning that were in some cases millennia old, and that his investigations were probably hampered by the lack of preservation techniques available at the time. Leonardo's detailed drawing of the internal organs of a woman (See left) reveal many traditional misconceptions.

Leonardo's study of human anatomy led also to the design of an automaton which has come to be called Leonardo's robot, was probably made around the year 1495 but was rediscovered only in the 1950s.

Comparative anatomy

Comparison of the leg of a man and a dog.

Leonardo not only studied human anatomy, but the anatomy of many other animals as well. He dissected cows, birds, monkeys and frogs, comparing in his drawings their anatomical structure with that of humans. On one page of his journal Leonardo drew five profile studies of a horse with its teeth bared in anger and, for comparison, a snarling lion and a snarling man.
I have found that in the composition of the human body as compared with the bodies of animals, the organs of sense are duller and coarser... I have seen in the Lion tribe that the sense of smell is connected with part of the substance of the brain which comes down the nostrils, which form a spacious receptacle for the sense of smell, which enters by a great number of cartilaginous vesicles with several passages leading up to where the brain, as before said, comes down.
In the early 1490s Leonardo was commissioned to create a monument in honor of Francesco Sforza. In his notebooks are a series of plans for an equestrian monument. There are also a large number of related anatomical studies of horses. They include several diagrams of a standing horse with the angles and proportions annotated, anatomical studies of horses' heads, a dozen detailed drawings of hooves and numerous studies and sketches of horses rearing. 

He studied the topographical anatomy of a bear in detail, making many drawings of its paws. There is also a drawing of the muscles and tendons of the bear's hind feet. Other drawings of particular interest include the uterus of a pregnant cow, the hindquarters of a decrepit mule and studies of the musculature of a little dog.

Botany

Leonardo wrote:
All the branches of a tree at every stage of its height when put together are equal in thickness to the trunk [below them].
The science of botany was long established by Leonardo's time, a treatise on the subject having been written as early as 300 BCE. Leonardo's study of plants, resulting in many beautiful drawings in his notebooks, was not to record in diagramatic form the parts of the plant, but rather, as an artist and observer to record the precise appearance of plants, the manner of growth and the way that individual plants and flowers of a single variety differed from one another. 

Study of sedge

One such study shows a page with several species of flower of which ten drawings are of wild violets. Along with a drawing of the growing plant and a detail of a leaf, Leonardo has repeatedly drawn single flowers from different angles, with their heads set differently on the stem.

Apart from flowers the notebooks contain many drawings of crop plants including several types of grain and a variety of berries including a detailed study of bramble. There are also water plants such as irises and sedge. His notebooks also direct the artist to observe how light reflects from foliage at different distances and under different atmospheric conditions

A number of the drawings have their equivalents in Leonardo's paintings. An elegant study of a stem of lilies may have been for one of Leonardo's early Annunciation paintings, carried in the hand of the Archangel Gabriel. In both the Annunciation pictures the grass is dotted with blossoming plants. 

The plants which appear in both the versions of The Virgin of the Rocks demonstrate the results of Leonardo's studies in a meticulous realism that makes each plant readily identifiable to the botanist.

Geology

A topographical map

As an adult, Leonardo had only two childhood memories, one of which was the finding of a cave in the Apennines. Although fearing that he might be attacked by a wild beast, he ventured in driven "by the burning desire to see whether there might be any marvelous thing within." 

Leonardo's earliest dated drawing is a study of the Arno Valley, strongly emphasizing its geological features. His notebooks contain landscapes with a wealth of geological observation from the regions of both Florence and Milan, often including atmospheric effects such as a heavy rainstorm pouring down on a town at the foot of a mountain range.

It had been observed for many years that strata in mountains often contained bands of sea shells. Conservative science said that these could be explained by the Great Flood described in the Bible. Leonardo's observations convinced him that this could not possibly be the case. 

And a little beyond the sandstone conglomerate, a tufa has been formed, where it turned towards Castel Florentino; farther on, the mud was deposited in which the shells lived, and which rose in layers according to the levels at which the turbid Arno flowed into that sea. And from time to time the bottom of the sea was raised, depositing these shells in layers, as may be seen in the cutting at Colle Gonzoli, laid open by the Arno which is wearing away the base of it; in which cutting the said layers of shells are very plainly to be seen in clay of a bluish colour, and various marine objects are found there.
This quotation makes clear the breadth of Leonardo's understanding of geology, including the action of water in creating sedimentary rock, the tectonic action of the Earth in raising the sea bed and the action of erosion in the creation of geographical features

In Leonardo's earliest paintings we see the remarkable attention given to the small landscapes of the background, with lakes and water, swathed in a misty light. In the larger of the Annunciation paintings is a town on the edge of a lake. Although distant, the mountains can be seen to be scored by vertical strata. This characteristic can be observed in other paintings by Leonardo, and closely resembles the mountains around Lago di Garda and Lago d'Iseo in Northern Italy. It is a particular feature of both the paintings of The Virgin of the Rocks, which also include caverns of fractured, tumbled, and water-eroded limestone.

Cartography

Leonardo's accurate map of Imola for Cesare Borgia.
 
In the early 16th century maps were rare and often inaccurate. Leonardo produced several extremely accurate maps such as the town plan of Imola created in 1502 in order to win the patronage of Cesare Borgia. Borgia was so impressed that he hired him as a military engineer and architect. Leonardo also produced a map of Chiana Valley in Tuscany, which he surveyed, without the benefit of modern equipment, by pacing the distances. In 1515, Leonardo produced a map of the Roman Southern Coast which is linked to his work for the Vatican and relates to his plans to drain the marshland. 

Recent research by Donato Pezzutto suggests that the background landscapes in Leonardo’s paintings depict specific locations as aerial views with enhanced depth, employing a technique called cartographic perspective. Pezzutto identifies the location of the Mona Lisa to the Val di Chiana, the Annunciation to the Arno Valley, the Madonna of the Yarnwinder to the Adda Valley and The Virgin and Child with St Anne to the Sessia Valley.

Hydrodynamics

Studies of water
 
Leonardo wrote:
All the branches of a water [course] at every stage of its course, if they are of equal rapidity, are equal to the body of the main stream.
Among Leonardo's drawings are many that are studies of the motion of water, in particular the forms taken by fast-flowing water on striking different surfaces. 

Many of these drawings depict the spiraling nature of water. The spiral form had been studied in the art of the Classical era and strict mathematical proportion had been applied to its use in art and architecture. An awareness of these rules of proportion had been revived in the early Renaissance. In Leonardo's drawings can be seen the investigation of the spiral as it occurs in water. 

There are several elaborate drawings of water curling over an object placed at a diagonal to its course. There are several drawings of water dropping from a height and curling upwards in spiral forms. One such drawing, as well as curling waves, shows splashes and details of spray and bubbles. 

Leonardo's interest manifested itself in the drawing of streams and rivers, the action of water in eroding rocks, and the cataclysmic action of water in floods and tidal waves. The knowledge that he gained from his studies was employed in devising a range of projects, particularly in relation to the Arno River. None of the major works was brought to completion.

Astronomy

The earth is not in the center of the Sun’s orbit nor at the center of the universe, but in the center of its companion elements, and united with them. And any one standing on the moon, when it and the sun are both beneath us, would see this our earth and the element of water upon it just as we see the moon, and the earth would light it as it lights us.

Alchemy

Claims are sometimes made that Leonardo da Vinci was an alchemist. He was trained in the workshop of Verrocchio, who according to Vasari, was an able alchemist. Leonardo was a chemist in so much as that he experimented with different media for suspending paint pigment. In the painting of murals, his experiments resulted in notorious failures with the Last Supper deteriorating within a century, and the Battle of Anghiari running off the wall. In Leonardo's many pages of notes about artistic processes, there are some that pertain to the use of silver and gold in artworks, information he would have learned as a student.

Leonardo's scientific process was based mainly upon observation. His practical experiments are also founded in observation rather than belief. Leonardo, who questioned the order of the solar system and the deposit of fossils by the Great Flood, had little time for the alchemical quests to turn lead into gold or create a potion that gave eternal life.

Leonardo said about alchemists:
The false interpreters of nature declare that quicksilver is the common seed of every metal, not remembering that nature varies the seed according to the variety of the things she desires to produce in the world.
Old alchemists... have never either by chance or by experiment succeeded in creating the smallest element that can be created by nature; however [they] deserve unmeasured praise for the usefulness of things invented for the use of men, and would deserve it even more if they had not been the inventors of noxious things like poisons and other similar things which destroy life or mind."
And many have made a trade of delusions and false miracles, deceiving the stupid multitude.

Mathematical studies

Perspective

The art of perspective is of such a nature as to make what is flat appear in relief and what is in relief flat.
During the early 15th century, both Brunelleschi and Alberti made studies of linear perspective. In 1436 Alberti published "della Pittura" ("On Painting"), which includes his findings on linear perspective. Piero della Francesca carried his work forward and by the 1470s a number of artists were able to produce works of art that demonstrated a full understanding of the principles of linear perspective

Draft of the perspective for Adoration of the Magi
 
Leonardo studied linear perspective and employed it in his earlier paintings. His use of perspective in the two Annunciations is daring, as he uses various features such as the corner of a building, a walled garden and a path to contrast enclosure and spaciousness. 

The unfinished Adoration of the Magi was intended to be a masterpiece revealing much of Leonardo's knowledge of figure drawing and perspective. There exists a number of studies that he made, including a detailed study of the perspective, showing the complex background of ruined Classical buildings that he planned for the left of the picture. In addition, Leonardo is credited with the first use of anamorphosis, the use of a "perspective" to produce an image that is intelligible only with a curved mirror or from a specific vantage point.

Leonardo wrote:
Those who are in love with practice without knowledge are like the sailor who gets into a ship without rudder or compass and who never can be certain whether he is going. Practice must always be founded on sound theory, and to this Perspective is the guide and the gateway; and without this nothing can be done well in the matter of drawing.

Geometry

The rhombicuboctahedron, as published in De divina proportione.
 
While in Milan in 1496 Leonardo met a traveling monk and academic, Luca Pacioli. Under him, Leonardo studied mathematics. Pacioli, who first codified and recorded the double entry system of bookkeeping, had already published a major treatise on mathematical knowledge, collaborated with Leonardo in the production of a book called "De divina proportione" about mathematical and artistic proportion. Leonardo prepared a series of drawings of regular solids in a skeletal form to be engraved as plates. "De divina proportione" was published in 1509.
All the problems of perspective are made clear by the five terms of mathematicians, which are:—the point, the line, the angle, the superficies and the solid. The point is unique of its kind. And the point has neither height, breadth, length, nor depth, whence it is to be regarded as indivisible and as having no dimensions in space.

Engineering and invention

Vasari in Lives of the Artists says of Leonardo:
He made designs for mills, fulling machines and engines that could be driven by water-power... In addition he used to make models and plans showing how to excavate and tunnel through mountains without difficulty, so as to pass from one level to another; and he demonstrated how to lift and draw great weights by means of levers, hoists and winches, and ways of cleansing harbours and using pumps to suck up water from great depths.

Practical inventions and projects

A machine for grinding convex lenses
 
Leonardo was a master of mechanical principles. He utilized leverage and cantilevering, pulleys, cranks, gears, including angle gears and rack and pinion gears; parallel linkage, lubrication systems and bearings. He understood the principles governing momentum, centripetal force, friction and the aerofoil and applied these to his inventions. His scientific studies remained unpublished with, for example, his manuscripts describing the processes governing friction predating the introduction of Amontons' Laws of Friction by 150 years.

It is impossible to say with any certainty how many or even which of his inventions passed into general and practical use, and thereby had impact over the lives of many people. Among those inventions that are credited with passing into general practical use are the strut bridge, the automated bobbin winder, the rolling mill, the machine for testing the tensile strength of wire and the lens-grinding machine pictured at right. In the lens-grinding machine, the hand rotation of the grinding wheel operates an angle-gear, which rotates a shaft, turning a geared dish in which sits the glass or crystal to be ground. A single action rotates both surfaces at a fixed speed ratio determined by the gear. 

As an inventor, Leonardo was not prepared to tell all that he knew:
How by means of a certain machine many people may stay some time under water. How and why I do not describe my method of remaining under water, or how long I can stay without eating; and I do not publish nor divulge these by reason of the evil nature of men who would use them as means of destruction at the bottom of the sea, by sending ships to the bottom, and sinking them together with the men in them. And although I will impart others, there is no danger in them; because the mouth of the tube, by which you breathe, is above the water supported on bags of corks.

Bridges and Hydraulics

Various hydraulic machines

Leonardo's study of the motion of water led him to design machinery that utilized its force. Much of his work on hydraulics was for Ludovico il Moro. Leonardo wrote to Ludovico describing his skills and what he could build:
…very light and strong bridges that can easily be carried, with which to pursue, and sometimes flee from, the enemy; and others safe and indestructible by fire or assault, easy and convenient to transport and place into position.
Among his projects in Florence was one to divert the course of the Arno, in order to flood Pisa. Fortunately, this was too costly to be carried out. He also surveyed Venice and came up with a plan to create a movable dyke for the city's protection against invaders. 

In 1502, Leonardo produced a drawing of a single span 240 m (720 ft) bridge as part of a civil engineering project for Ottoman Sultan Beyazid II of Istanbul. The bridge was intended to span an inlet at the mouth of the Bosphorus known as the Golden Horn. Beyazid did not pursue the project, because he believed that such a construction was impossible. Leonardo's vision was resurrected in 2001 when a smaller bridge based on his design was constructed in Norway.

War machines

An arsenal

Leonardo's letter to Ludovico il Moro assured him:
When a place is besieged I know how to cut off water from the trenches and construct an infinite variety of bridges, mantlets and scaling ladders, and other instruments pertaining to sieges. I also have types of mortars that are very convenient and easy to transport.... when a place cannot be reduced by the method of bombardment either because of its height or its location, I have methods for destroying any fortress or other stronghold, even if it be founded upon rock. ....If the engagement be at sea, I have many engines of a kind most efficient for offense and defense, and ships that can resist cannons and powder.
In Leonardo's notebooks there is an array of war machines which includes a vehicle to be propelled by two men powering crank shafts. Although the drawing itself looks quite finished, the mechanics were apparently not fully developed because, if built as drawn, the vehicle would never progress in a forward direction. In a BBC documentary, a military team built the machine and changed the gears in order to make the machine work. It has been suggested that Leonardo deliberately left this error in the design, in order to prevent it from being put to practice by unauthorized people. Another machine, propelled by horses with a pillion rider, carries in front of it four scythes mounted on a revolving gear, turned by a shaft driven by the wheels of a cart behind the horses. 

Leonardo's proposed vehicle
 
Leonardo's notebooks also show cannons which he claimed "to hurl small stones like a storm with the smoke of these causing great terror to the enemy, and great loss and confusion." He also designed an enormous crossbow. Following his detailed drawing, one was constructed by the British Army, but could not be made to fire successfully. In 1481 Leonardo designed a breech-loading, water cooled cannon with three racks of barrels allowed the re-loading of one rack while another was being fired and thus maintaining continuous fire power. The "fan type" gun with its array of horizontal barrels allowed for a wide scattering of shot. 

Leonardo was the first to sketch the wheel-lock musket c. 1500 AD (the precedent of the flintlock musket which first appeared in Europe by 1547), although as early as the 14th century the Chinese had used a flintlock 'steel wheel' in order to detonate land mines.

While Leonardo was working in Venice, he drew a sketch for an early diving suit, to be used in the destruction of enemy ships entering Venetian waters. A suit was constructed for a BBC documentary using pigskin treated with fish oil to repel water. The head was covered by a helmet with two eyeglasses at the front. A breathing tube of bamboo with pigskin joints was attached to the back of the helmet and connected to a float of cork and wood. When the scuba divers tested the suit, they found it to be a workable precursor to a modern diving suit, the cork float acting as a compressed air chamber when submerged. His inventions were very futuristic which meant they were very expensive and proved not to be useful.

Flight

The flight of a bird
 
In Leonardo's infancy a hawk had once hovered over his cradle. Recalling this incident, Leonardo saw it as prophetic.
An object offers as much resistance to the air as the air does to the object. You may see that the beating of its wings against the air supports a heavy eagle in the highest and rarest atmosphere, close to the sphere of elemental fire. Again you may see the air in motion over the sea, fill the swelling sails and drive heavily laden ships. From these instances, and the reasons given, a man with wings large enough and duly connected might learn to overcome the resistance of the air, and by conquering it, succeed in subjugating it and rising above it.
Design for a flying machine with wings based closely upon the structure of a bat's wings.

The desire to fly is expressed in the many studies and drawings. His later journals contain a detailed study of the flight of birds and several different designs for wings based in structure upon those of bats which he described as being less heavy because of the impenetrable nature of the membrane. There is a legend that Leonardo tested the flying machine on Monte Ceceri with one of his apprentices, and that the apprentice fell and broke his leg. Experts Martin Kemp and Liana Bortolon agree that there is no evidence of such a test, which is not mentioned in his journals. 

One design that he produced shows a flying machine to be lifted by a man-powered rotor. It would not have worked since the body of the craft itself would have rotated in the opposite direction to the rotor.

While he designed a number of man powered flying machines with mechanical wings that flapped, he also designed a parachute and a light hang glider which could have flown.

Musical instrument

The viola organista was an experimental musical instrument invented by Leonardo da Vinci. It was the first bowed keyboard instrument (of which any record has survived) ever to be devised. 

Leonardo's original idea, as preserved in his notebooks of 1488–1489 and in the drawings in the Codex Atlanticus, was to use one or more wheels, continuously rotating, each of which pulled a looping bow, rather like a fanbelt in an automobile engine, and perpendicular to the instrument's strings.

Leonardo's inventions made reality

Model of a flying machine by Leonardo in the V&A museum
 
In the late 20th century, interest in Leonardo's inventions escalated. There have been many projects which have sought to turn diagrams on paper into working models. One of the factors is the awareness that, although in the 15th and 16th centuries Leonardo had available a limited range of materials, modern technological advancements have made available a number of robust materials of light-weight which might turn Leonardo's designs into reality. This is particularly the case with his designs for flying machines. 

A difficulty encountered in the creation of models is that often Leonardo had not entirely thought through the mechanics of a machine before he drew it, or else he used a sort of graphic shorthand, simply not bothering to draw a gear or a lever at a point where one is essential in order to make a machine function. This lack of refinement of mechanical details can cause considerable confusion. Thus many models that are created, such as some of those on display at Clos Luce, Leonardo's home in France, do not work, but would work, with a little mechanical tweaking.

Exhibitions

  • Leonardo da Vinci Gallery at Museo Nazionale della Scienza e della Tecnologia "Leonardo da Vinci" in Milan; permanent exhibition, the biggest collection of Leonardo's projects and inventions.
  • Models of Leonardo's designs are on permanent display at Clos Luce.
  • The Victoria and Albert Museum, London, held an exhibition called "Leonardo da Vinci: Experience, Experiment and Design" in 2006
  • Logitech Museum
  • "The Da Vinci Machines Exhibition" was held in a pavilion in the Cultural Forecourt, at South Bank, Brisbane, Queensland, Australia in 2009. The exhibits shown were on loan from the Museum of Leonardo da Vinci, Florence, Italy.

Television programs

  • The U.S. Public Broadcasting Service (PBS), aired in October 2005, a television program called Leonardo's Dream Machines, about the building and successful flight of a glider based upon Leonardo's design.
  • The Discovery Channel began a series called Doing DaVinci in April 2009, in which a team of builders try to construct various da Vinci inventions based on his designs.

How can I logically manage to deceive myself? Buddhist thought offers a way out of the philosophical paradox

Edited by Sam Dresser















Self-deception seems inescapably paradoxical. For the self to be both the subject and the object of deceit, one and the same individual must devise the deceptive strategy by which they are hoodwinked. This seems impossible. For a trick to work effectively as a trick, one cannot know how it works. Equally, it is hard to see how someone can believe and disbelieve the same proposition. Holding p and not-p together is, straightforwardly, to contradict oneself. 

Despite its seemingly paradoxical qualities, many people claim to know first-hand what it is to be self-deceived. In fact, philosophers joke that only prolific self-deceivers would deny that they experience it. Nevertheless, there are skeptics who argue that self-deception is a conceptual impossibility so there can be no genuine cases, just as there can be no square-circles.

Yet self-deception seems undeniable in spite of its alleged incoherence. For the fact is, we are not always entirely rational. Certain situations, such as falling in love or being in the frenzied grips of grief, heighten susceptibility to self-deception. Betrayed lovers everywhere, anxious to discard the damning evidence of infidelity, know precisely Shakespeare’s meaning at sonnet 138:
When my love swears that she is made of truth,
I do believe her, though I know she lies
Self-deception is so curious a thing that it is a source of intrigue in the arts and sciences alike. Biologists such as Robert Trivers, for example, have begun to investigate self-deception’s evolutionary origins, probing its function and potential value.

On the one hand, evidence suggests that specific instances of self-deception can enhance well being and even prolong life. For example, multiple studies have found that optimistic individuals have better survival rates when diagnosed with cancer and other chronic illnesses, whereas ‘realistic acceptance’ of one’s prognosis has been linked to decreased life expectancy. On the other hand, self-deception seems like the ultimate delusion. Simultaneous belief and disbelief in a proposition is surely symptomatic of irrationality, placing one’s mental health and capacity for reason in jeopardy.

Existing debates face the challenge of connecting the philosophical and the practical aspects of the problem. Either self-deception is ruled out as incoherent, or it is accepted as a brute fact. If the former, the skeptic must justify the countless cases where it appears to occur. If the latter, some serious revisions to our conception of self are required.

Ideally, we should seek a single solution to both dimensions of the problem so that our explanation of self-deception also points the way to its prevention. For, while deceiving ourselves might occasionally seem to our advantage, in the long term it is self-alienating. And as we shall see, Buddhist approaches to self-deception achieve the synthesis of practical and philosophical resolutions more fully than do the dominant Western theories.
However, this contradicts psychoanalytic theories on the conscious and unconscious mind. It also goes against experience. We don’t always know ourselves as well as we think, and sometimes we convince ourselves of that which is evidently false or overwhelmingly improbable. The fine line between ambition and self-deception is often manifest around New Year, when many of us are forced to concede that our goals have crumbled from the heady heights of self-improvement plans into delusional wishful thinking.

If self-deception is paradoxical, the experience itself is even more perplexing. Unlike the immediacy of other experiences, how it feels to be self-deceived is knowable only retrospectively, after the spell has been broken.

Take Oedipus. Anxious that the prophecy of patricide and incest will be fulfilled, he leaves his home and family. Though he is genuinely shocked and sickened at the discovery of his true identity, there are indicators throughout the play to suggest his wilful ignorance. Given his fear of patricide, why does Oedipus continue blithely on his way after killing a man? Given his fear of committing incest, why does he marry a widow without first piecing the puzzle together? Such neglect leads the audience to suspect that, somehow, Oedipus was dimly aware of his identity before its full disclosure, and that he either repressed this awareness or deceived himself to avoid the painful truth.

Thankfully, for most of us, our small acts of repression, denial and self-deception are more mundane. For instance, data gathered through self-reporting on consumption often delivers distorted results, reflecting the respondents’ preferred self-image rather than any objective facts. It would be foolish to read self-deception into every omitted glass of wine or unrecorded biscuit – embarrassment and forgetfulness are equally plausible explanations. Even if self-deception is the root cause, this behavior seems fairly harmless.

Strategies of postponement and misrepresentation allow us to conceal our true nature even from ourselves.

Somewhere on the scale between extremely damaging and totally insignificant self-deception we find examples that resonate. If ancient wisdom traditions are right and the quest for self-knowledge is a fundamental part of human flourishing – as in the Socratic maxim ‘know thyself’ – then self-deception undermines the central aims of the good life. Convincing ourselves of what is manifestly false or impossible is both existentially crippling and socially harmful. This propensity is sometimes referred to as the mal du siècle: a general malaise triggered by unsettling awareness of our potential and identity.

In Being and Nothingness (1943), Jean-Paul Sartre invokes the concept of mauvaise foi, or bad faith, to explicate self-deception. He argues that many people are afraid to confront themselves, preferring to follow prescribed norms and fulfill pre-assigned roles rather than to strive for self-realization. He illustrates bad faith with a few examples: a woman’s hesitant reaction to a man’s advances, a waiter’s self-identification as ‘nothing more’ than a waiter, a homosexual’s unwillingness to acknowledge his sexuality. These strategies of postponement and misrepresentation allow the person to conceal their true nature even from themselves. Sartre deplores this mode of life, for, while such strategies might serve as effective coping mechanisms in the short term, in the long run they are existentially paralyzing.

This kind of self-deception, the sort backed up by conformity to norms or stereotypes, is extremely difficult to detect. And, naturally, the most pervasive forms of self-deceit are the hardest to root out. This is especially clear in cases of discrepancy between what a person professes, and how they feel or behave.

Of course, the presence of a bias does not automatically imply self-deception. People can discriminate unknowingly, even against their will, and there is a world of difference between ignorance, and wilful ignorance of one’s own biases and prejudices. As the US civil rights advocate Jesse Jackson put it in 1993: ‘There is nothing more painful to me at this stage in my life than to walk down the street and hear footsteps … then look around and see somebody white and feel relieved.’ Still, discrepancy between belief and behavior can sometimes signal self-deception, as can the language we use.

It is a mistake to treat the philosophical and the practical aspects of the problem of self-deception as entirely distinct. For what use is an explanation of this phenomenon unaccompanied by a strategy for its alleviation? Prominent Western theories on self-deception tend to leave the practical problem unresolved. But there is an alternative, Buddhist approach. The artful combination of three Buddhist theories provides a philosophically therapeutic perspective on self-deception. Before turning to this response, however, let’s delve deeper into the concept of self on which the paradox depends.

Skeptics about self-deception claim that any genuine examples would need to satisfy impossible conditions, such as the knowing-dupe or the contradictory belief conditions. They claim that satisfying the first condition means being duped by one’s own duplicitous scheme while satisfying the second is tantamount to abandoning reason. Such skepticism represents the minority view, since so many examples of this supposedly impossible phenomenon are clear. Yet it remains a theoretical option.

For the skeptic’s defeat we must show either: (1) that the fact of somebody holding inconsistent beliefs is reconcilable with the idea of a unified center of conscious beliefs; or (2) that the skeptic misconstrues the conditions under which self-deception occurs. Arguably, the skeptic’s account of self-deception reduces the complexities of human psychology to what is possible at one single moment in time, under the assumption that no sane, cognitively competent person simultaneously believes p and not-p.

But if this is an argument against self-deception, it is time to revise our model of selfhood. Indeed, far from precluding the possibility of self-deception, the multifaceted nature of consciousness might actually help to explain it.

Western philosophy has produced several responses to the paradox of self-deception, the most recurrent of which are the temporal partitioning and the psychological partitioning approaches. Both challenge the (still dominant) conception of the self as completely internally unified and fully self-aware. They are designed to show that self-deception is paradoxical only if the Cartesian model of the self as a non-composite, immaterial substance – whose purity we imagine we partake of – is accepted. Without this idea of the self, self-deception is a puzzle, but it is not a paradox.

Deceiving oneself is just a more unusual case of lying

Some leading philosophers in consciousness studies and the nature of mind reject the Cartesian concept of self. Aside from the lack of empirical evidence for such a self, it would surely be too abstract and impersonal to bear a connection with the individual of lived experience, who engages and interacts in the temporal world. But the influence of the Cartesian model has historically been so significant that it continues to shape the debate. Although both temporal partitioning and psychological partitioning proposals challenge this model of the self, they do not resolve the practical problem of eliminating self-deception.

Advocates of temporal partitioning might invoke the appointment case to explain how self-deception works. The philosopher Brian McLaughlin at Rutgers University in New Jersey summarizes it as follows:
In order to miss an unpleasant meeting three months ahead, Mary deliberately writes the wrong date for the meeting in her appointment book, a date later than the actual date of the meeting. She does this so that three months later when she consults the book, she will come mistakenly to believe the meeting is on that date and, as a result, miss the meeting.
This is supposed to show that self-deception does not require simultaneous belief in p and not-p. Instead, all that is required is an intention to induce the belief not-p at the time of believing p. In this case, there is no time when Mary believes both that her appointment is on Thursday and that it is on Friday. Rather, she relies on her faulty memory so that, when she eventually consults her diary, she will have forgotten her act of deception.

We can contest the likelihood of Mary’s forgetting. Indeed, if the prospective appointment (let’s say, with the dentist) elicits such a reaction, she will surely struggle to put it out of her mind. What matters though is that temporal partitioning challenges the idea that the act of deception and the experience of deceit must coincide. Deceiving oneself therefore largely resembles deceiving somebody else, and is just a more unusual case of lying.

For the skeptic, this account won’t cut it. The obvious objection is that temporal partitioning seems not so much to explain self-deception as to explain it away. After all, if after three months Mary has forgotten the true date of her appointment, doesn’t this show that the Mary who deceived is, in some sense, a different person from the Mary who is deceived? If we distinguish cases of self-deception from cases of self-induced deception, we might protest that the appointment case is an example only of the latter. And even if we are satisfied that temporal partitioning explains how self-deception occurs, it cannot tell us how to overcome it.

Another common explanation of self-deception appeals to psychological partitioning between the different facets of the self. On this view, self-deception does involve simultaneous assent to p and not-p but this is not paradoxical because of the multifaceted nature of the self. Rather than treat the self as fully integrated, we should see it as a process, the product of a complex structure composed of various elements. One part of the self can conceal its beliefs from another part, making self-deception possible.

It is only in moments of introspection that the illusion of a unified self is cast into doubt. An advantage of this theory is that it accommodates different levels of self-awareness within one individual, explaining discrepancies between the conscious and unconscious mind.

The philosopher Amélie Oksenberg Rorty at Harvard Medical School illustrates how this might work with the example of Dr Laetitia Androvna:
A specialist in the diagnosis of cancer, whose fascination for the obscure does not usually blind her to the obvious, she has begun to mis-describe and ignore symptoms that the most junior premedical student would recognize as the unmistakable symptoms of the late stages of a currently incurable form of cancer.
Androvna deflects the questions of her concerned colleagues away from her condition, though she does put her affairs in order (eg, by making a will). The mismatch between her behavior and her consciously held beliefs suggests that, at some level, she recognizes her illness but is finding ways to keep her conflicting acknowledgements apart.

Again, the skeptic argues that psychological partitioning is incompatible with genuine instances of self-deception because this approach likewise undermines the identity of deceiver and deceived. From this perspective, if the self is divisible then, to be sure, one part might deceive another, but is this self-deception? If we challenge the unity of the self, must we also challenge the idea of self-deception?

According to Buddhism, the answer is no.

Early Buddhists did not explicitly discuss the problem of self-deception, at least not as it’s understood in Western philosophy. What they did do, however, was provide detailed accounts of three theories that, collectively, provide a response to both the philosophical and practical aspects of the problem. These are (1) the theory of no-self (anātman); (2) the theory of wilful ignorance (avidyā); and (3) the theory of two truths (satyadvaya).

These teachings are variously interpreted within Buddhism, but all schools agree that they can provide transformative insights into our own nature, banishing our tendency for self-deception. While we’re inclined to treat self-deception as the exception rather than the rule, Buddhists see it as our default position. They claim that most people repress and deny uncomfortable truths, deceiving themselves on an almost unimaginable scale about all manner of things. From the Buddhist point of view, the skeptic’s only success lies in the extent of their self-deceit: by defining the self in ways that make it impervious to change, they also strip it of potential.

Specifically, Buddhists claim that we routinely convince ourselves that what is perishable and impermanent can be a lasting source of satisfaction. This illusion only reinforces our existential situation, which is one of profound suffering. From this perspective, even when false beliefs offer temporary relief from painful truths, self-deception merely prolongs the inevitable. Since none of us can stave off our demise forever, each of us is eventually forced to confront the reality of our own transience.

The remedy to all this is a fearless acceptance of our own impermanence and insubstantiality. By abandoning our self-image as fixed centers of agency, Buddhists argue that we eliminate the stultifying effects of greed and hatred borne from egoism. This process eventually leads to liberation through self-awareness, consisting of awareness of the fundamental lack of any self at all.

No-self (anātman) is Buddhism’s most famous, but also most frequently misunderstood, theory. Buddhists supply several arguments against the existence of an eternal, changeless, transcendental and metaphysical self. To understand these arguments, we must contextualize them against the backdrop of the Vedic view of the self, dominant in classical India. In the Vedic worldview, the innermost kernel of a person, the ātman, corresponds to the fundamental source and ground of reality, the Brahman, which is essentially unchanging.

Buddhists reject this on two fronts. First, if the self existed in this way, it could not engage in worldly experience but would instead stand inertly outside of time and space. It would thus bear no relation to the human person who lives and changes through time. Moreover, since experience confirms that everything is causally conditioned, hence subject to change and degradation, an immutable self could never be empirically observed. Second, Buddhists argue that obsession with a fixed self is morally problematic, and that this belief perpetuates selfishness. Belief in the self is therefore seen as both the symptom and the cause of deluded attachment.

The human person is a process, not a thing.

Ironically, then, Buddhists are inclined to see belief in a single substantial self as the severest, most dangerous instance of self-deception. This immediately raises the question: if there is no-self, who can be the subject of self-deceit? To answer, we must invoke the theory of two truths (satyadvaya), which stipulates a distinction between ultimate and conventional truth.

In his study of self-deception in different traditions, the philosopher Eliot Deutsch of the University of Hawaii demonstrates one of the ways in which the no-self theory is often misconstrued. He argues that Buddhists can ‘have little to say’ about self-deception because they do not accept the ultimate reality of the metaphysical self. If this disqualifies Buddhists from debates on self-deception, it must also disqualify many Western philosophers who do not approach the paradox of self-deception with a unitary self in mind (including advocates of temporal and psychological partitioning).

On the contrary, although Buddhists reject the ultimate existence of the self, they accept the conventional (we might say, practical or functional) reality of conceptually constructed persons. And crucially, as we have seen, it is the conventional person – not an ultimate self – who expresses the full range of human emotions and deploys the tactics of self-manipulation, including self-deception.

Buddhists conceive of conventional reality in terms of conceptualization. Hence, the concept of a person reflects nothing more than the imposition of this idea on to ephemeral elements of which we are composed, called the skandhas. The skandhas include: the physical body, sensory experiences, cognitive awareness of perceptions, intentional acts of will and consciousness. None of these remain stable over time but there is a causal connection between the past, present and future skandhas. This is sufficient for personal identity even though there is no such thing as a numerically identical self.

In other words, the human person is a process, not a thing. Our language typically fails to communicate this fact, and my repeated use of the word ‘I’ sustains the illusion of the self as an underlying, constant feature of reality.

To explain how self-deception occurs, Buddhists can distinguish ultimate from conventional truth. Like the temporal and psychological partitioning approaches, epistemic partitioning challenges the identity of deceiver and deceived. At the level of ultimate truth, there simply is no-self who could be self-deceived. At the level of conventional truth, we encounter the person (who is an illusion, better thought of as a sequence of person-stages). Unlike temporal and psychological partitioning, however, epistemic partitioning goes a step further. It not only explains the mechanism of self-deception but also contains the seeds of its elimination.

The Buddha’s teachings are renowned for their therapeutic orientation, and self-deception seems the antithesis of an authentic life of human flourishing. Buddhism stresses the link between discerning truth (with ‘right view’ as the first step on the noble eightfold path) and moral fulfillment. The distinction between ultimate and conventional truth not only explains the origins of our illusions but helps us to overcome, or see through, their deceptive character.

The final goal of this process is the complete alleviation of suffering, including the suffering borne out of self-deception. Epistemic partitioning of ultimate and conventional knowledge results in two modes of knowing, which we might call the cognitive/intellectual and the affective/practical. We might know ultimately that everything is impermanent and insubstantial yet remain attached to merely conventional things. Ourselves, for instance.

We display wilful ignorance of perishability as we cannot bear to lose the things we hold most dear
Once we internalize this truth, however, Buddhists suppose that delusional compulsions for transient things will be gradually undermined. Just as there is no ultimately real self, neither are there any ultimately real tables, chairs and so forth. The identity we assign to composite things made up of parts is just the product of mental construction, reflecting our ingrained tendency to impose structure, stability and substance.

Though we know that things change and degrade, we act as though they are permanent. Such a discrepancy between conscious cognitive belief and innate affective attitude signals self-deceit. Put simply, we display wilful ignorance (avidyā) of perishability because we cannot bear to lose the things we hold most dear.

Why, then, do Buddhists treat conventional truths as truths at all? Indeed, if they are nothing but convenient fictions, isn’t this a distortion of truth’s meaning? Again, Buddhists see the therapeutic dimension of their philosophy as justifying this manoeuvre: belief in the self would be both inaccurate and unhelpful, whereas belief in the person is key to accomplishing the goals of Buddhism. Mindfulness forces us first to confront the wide chasm between our self-image and the ultimate truth of our nature; and second, helps us to bridge that chasm by becoming increasingly aware of the workings of the mind and its deceptive strategies so that we no longer repress and deny our true feelings.

It might strike the modern reader as patently wrongheaded to suggest that any religious tradition contains the seeds of a solution more satisfying than secular proposals. For, understandably, many see religious belief as coterminous with wishful thinking and incompatible with reason. However, the Buddhist response sketched here depends exclusively on arguments about human nature that are equally open to dispute and defense. There is no recourse to mystical or non-empirical claims. And because the problem of self-deception is more personal than many of philosophy’s other problems, viable solutions must work both in theory and in practice. Though the many forms of self-deception make the effectiveness of a universally applicable remedy unlikely, Buddhists would concur with Macbeth’s doctor that ‘Therein the patient must minister to himself.’

Renaissance technology

From Wikipedia, the free encyclopedia

Renaissance technology is the set of European artifacts and inventions which span the Renaissance period, roughly the 14th century through the 16th century. The era is marked by profound technical advancements such as the printing press, linear perspective in drawing, patent law, double shell domes and Bastion fortresses. Sketchbooks from artisans of the period (Taccola and Leonardo da Vinci, example) give a deep insight into the mechanical technology then known and applied.
 
Renaissance science spawned the Scientific Revolution; science and technology began a cycle of mutual advancement.

Basic technology

Some important Renaissance technologies, including both innovations and improvements on existing techniques:

Late 14th century

Some of the technologies were the arquebus and the musket.

15th century

The technologies that developed in Europe during the second half of the 15th century were commonly associated by authorities of the time with a key theme in Renaissance thought: the rivalry of the Moderns and the Ancients. Three inventions in particular — the printing press, firearms, and the nautical compass — were indeed seen as evidence that the Moderns could not only compete with the Ancients, but had surpassed them, for these three inventions allowed modern people to communicate, exercise power, and finally travel at distances unimaginable in earlier times.


Water-raising pump powered by crank and connecting rod mechanism (Georg Andreas Böckler, 1661)

The crank and connecting rod mechanism which converts circular into reciprocal motion is of utmost importance for the mechanization of work processes; it is first attested for Roman water-powered sawmills. During the Renaissance, its use is greatly diversified and mechanically refined; now connecting-rods are also applied to double compound cranks, while the flywheel is employed to get these cranks over the 'dead-spot'. Early evidence of such machines appears, among other things, in the works of the 15th-century engineers Anonymous of the Hussite Wars and Taccola. From then on, cranks and connecting rods become an integral part of machine design and are applied in ever more elaborate ways: Agostino Ramelli's The Diverse and Artifactitious Machines of 1588 depicts eighteen different applications, a number which rises in the 17th-century Theatrum Machinarum Novum by Georg Andreas Böckler to forty-five.

Printing press

Two printers operating a Gutenberg-style printing press (1568). Such presses could make around 3,600 impressions per workday.
 
The invention of the printing press by the German goldsmith Johannes Gutenberg (1398–1468) is widely regarded as the single most important event of the second millennium, and is one of the defining moments of the Renaissance. The Printing Revolution which it sparks throughout Europe works as a modern "agent of change" in the transformation of medieval society.

The mechanical device consists of a screw press modified for printing purposes which can produce 3,600 pages per workday, allowing the mass production of printed books on a proto-industrial scale. By the start of the 16th century, printing presses are operating in over 200 cities in a dozen European countries, producing more than twenty million volumes. By 1600, their output had risen tenfold to an estimated 150 to 200 million copies, while Gutenberg book printing spread from Europe further afield.

The relatively free flow of information transcends borders and induced a sharp rise in Renaissance literacy, learning and education; the circulation of (revolutionary) ideas among the rising middle classes, but also the peasants, threatens the traditional power monopoly of the ruling nobility and is a key factor in the rapid spread of the Protestant Reformation. The dawn of the Gutenberg Galaxy, the era of mass communication, is instrumental in fostering the gradual democratization of knowledge which sees for the first time modern media phenomena such as the press or bestsellers emerging. The prized incunables, which are testimony to the aesthetic taste and high proficient competence of Renaissance book printers, are one lasting legacy of the 15th century. 

Parachute

Veranzio's 1595 parachute design titled "Flying Man"

The earliest known parachute design appears in an anonymous manuscript from 1470s Renaissance Italy; it depicts a free-hanging man clutching a crossbar frame attached to a conical canopy. As a safety measure, four straps run from the ends of the rods to a waist belt. Around 1485, a more advanced parachute was sketched by the polymath Leonardo da Vinci in his Codex Atlanticus (fol. 381v), which he scales in a more favorable proportion to the weight of the jumper. Leonardo's canopy was held open by a square wooden frame, altering the shape of the parachute from conical to pyramidal. The Venetian inventor Fausto Veranzio (1551–1617) modifies da Vinci's parachute sketch by keeping the square frame, but replacing the canopy with a bulging sail-like piece of cloth. This he realized decelerates the fall more effectively. Claims that Veranzio successfully tested his parachute design in 1617 by jumping from a tower in Venice cannot be substantiated; since he was around 65 years old at the time, it seems unlikely.

Mariner's astrolabe

The earliest recorded uses of the astrolabe for navigational purposes are by the Portuguese explorers Diogo de Azambuja (1481), Bartholomew Diaz (1487/88) and Vasco da Gama (1497/98) during their sea voyages around Africa.

Dry dock

While dry docks were already known in Hellenistic shipbuilding, these facilities were reintroduced in 1495/96, when Henry VII of England ordered one to be built at the Portsmouth navy base.

16th century

Floating dock

Floating dock at Venice (1560)

The earliest known description of a floating dock comes from a small Italian book printed in Venice in 1560, titled Descrittione dell'artifitiosa machina. In the booklet, an unknown author asks for the privilege of using a new method for the salvaging of a grounded ship and then proceeds to describe and illustrate his approach. The included woodcut shows a ship flanked by two large floating trestles, forming a roof above the vessel. The ship is pulled in an upright position by a number of ropes attached to the superstructure.

Lifting tower

Relocation of the Vatican Obelisk, Rome, by Domenico Fontana (1586)
 
A lifting tower was used to great effect by Domenico Fontana to relocate the monolithic Vatican obelisk in Rome. Its weight of 361 t was far greater than any of the blocks the Romans are known to have lifted by cranes.

A water-powered mine hoist used for raising ore, ca. 1556

Mining, machinery and chemistry

A standard reference for the state of mechanical arts during the Renaissance is given in the mining engineering treatise De re metallica (1556), which also contains sections on geology, mining and chemistry. De re metallica was the standard chemistry reference for the next 180 years.

Early 17th century

Newspaper
 
Title page of the Relation (1609), the earliest newspaper
 
The newspaper is an offspring of the printing press from which the press derives its name. The 16th century sees a rising demand for up-to-date information which can not be covered effectively by the circulating hand-written newssheets. For "gaining time" from the slow copying process, Johann Carolus of Strassburg is the first to publish his German-language Relation by using a printing press (1605). In rapid succession, further German newspapers are established in Wolfenbüttel (Avisa Relation oder Zeitung), Basel, Frankfurt and Berlin. From 1618 onwards, enterprising Dutch printers take up the practice and begin to provide the English and French market with translated news. By the mid-17th century it is estimated that political newspapers which enjoyed the widest popularity reach up to 250,000 readers in the Holy Roman Empire, around one quarter of the literate population.

Air-gun

In 1607 Bartolomeo Crescentio described an air-gun equipped with a powerful spiral spring, a device so complex that it must have had predecessors. In 1610 Mersenne spoke in detail of "sclopeti pneumatici constructio", and four years later Wilkins wrote enthusiastically of "that late ingenious invention the wind-gun" as being "almost equall to our powder-guns". In the 1650s Otto von Guericke, famed for his experiments with vacua and pressures, built the Madeburger Windbuchse, one of the technical wonders of its time.

Tools, devices, work processes

15th century

Cranked Archimedes' screw
 
The German engineer Konrad Kyeser equips in his Bellifortis (1405) the Archimedes' screw with a crank mechanism which soon replaces the ancient practice of working the pipe by treading.

Cranked reel

In the textile industry, cranked reels for winding skeins of yarn were introduced in the early 15th century.

Brace

The earliest carpenter's braces equipped with a U-shaped grip, that is with a compound crank, appears between 1420 and 1430 in Flanders.

Cranked well-hoist
 
The earliest evidence for the fitting of a well-hoist with cranks is found in a miniature of c. 1425 in the German Hausbuch of the Mendel Foundation.

Paddle wheel boat powered by crank and connecting rod mechanism

While paddle wheel boats powered by manually turned crankshafts were already conceived of by earlier writers such as Guido da Vigevano and the Anonymous Author of the Hussite Wars, the Italian Roberto Valturio much improves on the design in 1463 by devising a boat with five sets of parallel cranks which are all joined to a single power source by one connecting rod; the idea is also taken up by his compatriot Francesco di Giorgio.

Rotary grindstone with treadle

Evidence for rotary grindstones operated by a crank handle goes back to the Carolingian Utrecht Psalter. Around 1480, the crank mechanism is further mechanized by adding a treadle.

Geared hand-mill

The geared hand-mill, operated either with one or two cranks, appears in the 15th century.

16th century

German grenade muskets from the 16th century (the two upper ones)
 
 
Two 16th-century German grenade muskets working with a wheellock mechanism are on display in the Bayerisches Nationalmuseum, Munich.

Technical drawings of artist-engineers

The revived scientific spirit of the age can perhaps be best exemplified by the voluminous corpus of technical drawings which the artist-engineers left behind, reflecting the wide variety of interests the Renaissance Homo universalis pursued. The establishment of the laws of linear perspective by Brunelleschi gave his successors, such as Taccola, Francesco di Giorgio Martini and Leonardo da Vinci, a powerful instrument to depict mechanical devices for the first time in a realistic manner. The extant sketch books give modern historians of science invaluable insights into the standards of technology of the time. Renaissance engineers showed a strong proclivity to experimental study, drawing a variety of technical devices, many of which appeared for the first time in history on paper.

However, these designs were not always intended to be put into practice, and often practical limitations impeded the application of the revolutionary designs. For example, da Vinci's ideas on the conical parachute or the winged flying machine were only applied much later. While earlier scholars showed a tendency to attribute inventions based on their first pictorial appearance to individual Renaissance engineers, modern scholarship is more prone to view the devices as products of a technical evolution which often went back to the Middle Ages.

Technology Date Author Treatise Comment
Pile driver 1475  Francesco di Giorgio Martini Trattato di Architectura Drawing of such a device whose principle must be according to the Brazilian historian of technology Ladislao Reti "considered original with Franceso".
Centrifugal pump 1475  Francesco di Giorgio Martini Trattato di Architectura Water or mud-lifting machine "that must be characterized as the prototype of the centrifugal pump".

Saturday, January 26, 2019

Renaissance humanism

From Wikipedia, the free encyclopedia

Leonardo da Vinci's Vitruvian Man (c. 1490) shows the correlations of ideal human body proportions with geometry described by the ancient Roman architect Vitruvius in his De Architectura. Vitruvius described the human figure as being like the principal source of proportion among the Classical orders of architecture.
 
Renaissance humanism is the study of classical antiquity, at first in Italy and then spreading across Western Europe in the 14th, 15th, and 16th centuries. The term humanism is contemporary to that period, while Renaissance humanism is a retronym used to distinguish it from later humanist developments.

Renaissance humanism was a response to the utilitarian approach and what came to be depicted as the "narrow pedantry" associated with medieval scholasticism. Humanists sought to create a Citizenry able to speak and write with eloquence and clarity and thus capable of engaging in the civic life of their communities and persuading others to virtuous and prudent actions. This was to be accomplished through the study of the studia humanitatis, today known as the humanities: grammar, rhetoric, history, poetry, and moral philosophy.

According to one scholar of the movement,
Early Italian humanism, which in many respects continued the grammatical and rhetorical traditions of the Middle Ages, not merely provided the old Trivium with a new and more ambitious name (Studia humanitatis), but also increased its actual scope, content and significance in the curriculum of the schools and universities and in its own extensive literary production. The studia humanitatis excluded logic, but they added to the traditional grammar and rhetoric not only history, Greek, and moral philosophy, but also made poetry, once a sequel of grammar and rhetoric, the most important member of the whole group.
Humanism was a pervasive cultural mode and not the program of a small elite, a program to revive the cultural legacy, literary legacy, and moral philosophy of classical antiquity. There were important centers of humanism in Florence, Naples, Rome, Venice, Genoa, Mantua, Ferrara, and Urbino.

Origin

Some of the first humanists were great collectors of antique manuscripts, including Petrarch, Giovanni Boccaccio, Coluccio Salutati, and Poggio Bracciolini. Of the four, Petrarch was dubbed the "Father of Humanism" because of his devotion or loyalty to Greek and Roman scrolls. Many worked for the Catholic Church and were in holy orders, like Petrarch, while others were lawyers and chancellors of Italian cities, and thus had access to book copying workshops, such as Petrarch's disciple Salutati, the Chancellor of Florence

In Italy, the humanist educational program won rapid acceptance and, by the mid-15th century, many of the upper classes had received humanist educations, possibly in addition to traditional scholasticist ones. Some of the highest officials of the Catholic Church were humanists with the resources to amass important libraries. Such was Cardinal Basilios Bessarion, a convert to the Catholic Church from Greek Orthodoxy, who was considered for the papacy, and was one of the most learned scholars of his time. There were several 15th-century and early 16th-century humanist Popes one of whom, Aeneas Silvius Piccolomini (Pope Pius II), was a prolific author and wrote a treatise on The Education of Boys. These subjects came to be known as the humanities, and the movement which they inspired is shown as humanism. 

The migration waves of Byzantine Greek scholars and émigrés in the period following the Crusader sacking of Constantinople and the end of the Byzantine Empire in 1453 greatly assisted the revival of Greek and Roman literature and science via their greater familiarity with ancient languages and works. They included Gemistus Pletho, George of Trebizond, Theodorus Gaza, and John Argyropoulos

Italian humanism spread northward to France, Germany, the Low Countries, and England with the adoption of large-scale printing after the end of the era of incunabula (or books printed prior to 1501), and it became associated with the Protestant Reformation. In France, pre-eminent humanist Guillaume Budé (1467–1540) applied the philological methods of Italian humanism to the study of antique coinage and to legal history, composing a detailed commentary on Justinian's Code. Budé was a royal absolutist (and not a republican like the early Italian umanisti) who was active in civic life, serving as a diplomat for François I and helping to found the Collège des Lecteurs Royaux (later the Collège de France). Meanwhile, Marguerite de Navarre, the sister of François I, was a poet, novelist, and religious mystic who gathered around her and protected a circle of vernacular poets and writers, including Clément Marot, Pierre de Ronsard, and François Rabelais.

Paganism and Christianity in the Renaissance

Many humanists were churchmen, most notably Pope Pius II (Aeneas Silvius Piccolomini), Sixtus IV, and Leo X, and there was often patronage of humanists by senior church figures. Much humanist effort went into improving the understanding and translations of Biblical and early Christian texts, both before and after the Protestant Reformation, which was greatly influenced by the work of non-Italian, Northern European figures such as Desiderius Erasmus, Jacques Lefèvre d'Étaples, William Grocyn, and Swedish Catholic Archbishop in exile Olaus Magnus.

The Cambridge Dictionary of Philosophy describes the rationalism of ancient writings as having tremendous impact on Renaissance scholars:
Here, one felt no weight of the supernatural pressing on the human mind, demanding homage and allegiance. Humanity—with all its distinct capabilities, talents, worries, problems, possibilities—was the center of interest. It has been said that medieval thinkers philosophised on their knees, but, bolstered by the new studies, they dared to stand up and to rise to full stature.
The rediscovery of classical philosophy and science would eventually challenge traditional religious beliefs. In 1417, for example, Poggio Bracciolini discovered the manuscript of Lucretius, De rerum natura, which had been lost for centuries and which contained an explanation of Epicurean doctrine, though at the time this was not commented on much by Renaissance scholars, who confined themselves to remarks about Lucretius's grammar and syntax. Lorenzo Valla, however, puts a defense of epicureanism in the mouth of one of the interlocutors of one of his dialogues. Valla's defense, or adaptation, of Epicureanism was later taken up in The Epicurean by Erasmus, the "Prince of humanists:"
If people who live agreeably are Epicureans, none are more truly Epicurean than the righteous and godly. And if it is names that bother us, no one better deserves the name of Epicurean than the revered founder and head of the Christian philosophy Christ, for in Greek epikouros means "helper." He alone, when the law of Nature was all but blotted out by sins, when the law of Moses incited to lists rather than cured them, when Satan ruled in the world unchallenged, brought timely aid to perishing humanity. Completely mistaken, therefore, are those who talk in their foolish fashion about Christ's having been sad and gloomy in character and calling upon us to follow a dismal mode of life. On the contrary, he alone shows the most enjoyable life of all and the one most full of true pleasure.
This passage exemplifies the way in which the humanists saw pagan classical works, such as the philosophy of Epicurus, as being in harmony with their interpretation of Christianity.

Renaissance Neo-Platonists such as Marsilio Ficino (whose translations of Plato's works into Latin were still used into the 19th century) attempted to reconcile Platonism with Christianity, according to the suggestions of early Church fathers Lactantius and Saint Augustine. In this spirit, Pico della Mirandola attempted to construct a syncretism of all religions (he was not a humanist but an Aristotelian trained in Paris), but his work did not win favor with the church authorities.

Historian Steven Kreis expresses a widespread view (derived from the 19th-century Swiss historian Jacob Burckhardt), when he writes that:
The period from the fourteenth century to the seventeenth worked in favor of the general emancipation of the individual. The city-states of northern Italy had come into contact with the diverse customs of the East, and gradually permitted expression in matters of taste and dress. The writings of Dante, and particularly the doctrines of Petrarch and humanists like Machiavelli, emphasized the virtues of intellectual freedom and individual expression. In the essays of Montaigne the individualistic view of life received perhaps the most persuasive and eloquent statement in the history of literature and philosophy.
Two noteworthy trends in Renaissance humanism were Renaissance Neo-Platonism and Hermeticism, which through the works of figures like Nicholas of Kues, Giordano Bruno, Cornelius Agrippa, Campanella and Pico della Mirandola sometimes came close to constituting a new religion itself. Of these two, Hermeticism has had great continuing influence in Western thought, while the former mostly dissipated as an intellectual trend, leading to movements in Western esotericism such as Theosophy and New Age thinking. The "Yates thesis" of Frances Yates holds that before falling out of favour, esoteric Renaissance thought introduced several concepts that were useful for the development of scientific method, though this remains a matter of controversy.

Though humanists continued to use their scholarship in the service of the church into the middle of the sixteenth century and beyond, the sharply confrontational religious atmosphere following the Protestant reformation resulted in the Counter-Reformation that sought to silence challenges to Catholic theology, with similar efforts among the Protestant denominations. However, a number of humanists joined the Reformation movement and took over leadership functions, for example, Philipp Melanchthon, Ulrich Zwingli, John Calvin, and William Tyndale.

With the Counter Reformation initiated by the Council of Trent (1545-1563), positions hardened and a strict Catholic orthodoxy based on Scholastic philosophy was imposed. Some humanists, even moderate Catholics such as Erasmus, risked being declared heretics for their perceived criticism of the church.

The historian of the Renaissance Sir John Hale cautions against too direct a linkage between Renaissance humanism and modern uses of the term humanism: "Renaissance humanism must be kept free from any hint of either "humanitarianism" or "humanism" in its modern sense of rational, non-religious approach to life ... the word "humanism" will mislead ... if it is seen in opposition to a Christianity its students in the main wished to supplement, not contradict, through their patient excavation of the sources of ancient God-inspired wisdom"

Inequality (mathematics)

From Wikipedia, the free encyclopedia https://en.wikipedia.org/wiki/Inequality...