Ultimate reality is "the supreme, final, and fundamental power in all reality". It refers to the most fundamental fact about reality, especially when it is seen as also being the most valuable fact. This may overlap with the concept of the Absolute in certain philosophies.
Greek philosophy
Anaximander (c. 610–546 BCE) believed that the ultimate substance of the universe, generally known as arche, was apeiron, an infinite and eternal substance that is the origin of all things.
Aristotle (384–322 BCE) held that the unmoved mover "must be an immortal, unchanging being, ultimately responsible for all wholeness and orderliness in the sensible world" and that its existence is necessary to support everyday change.
Democritus (c. 460–370 BCE) and Epicureanism (c. 307 BCE) rejected the idea of ultimate reality, saying that only atoms and void exist, but they do have the eternal, unbounded, and self-caused nature of non-materialistic views of the concept.
In Neoplatonism (3rd century CE), the first principle of reality is "the One" which is a perfectly simple and ineffable principle which is the source of the universe, and exists without multiplicity and beyond being and non-being.
Stoic physics (c. 300 BCE–3rd century CE) called the primitive substance of the universe pneuma or God, which is everything that exists and is a creative force that develops and shapes the cosmos.
Buddhism
In Theravada Buddhism, Nirvana is ultimate reality. Nirvana is described in negative terms; it is unconstructed and unconditioned.
In some strands of Mahayana Buddhism, the Buddha-nature or the Dharmakaya is seen as ultimate reality.
Other strands of Buddhism reject the notion of ultimate reality, regarding any existent as empty (sunyata) of inherent existence (svabhava).
Hinduism
In Hinduism, Brahman connotes the highest universal principle, the ultimate reality in the universe. In major schools of Hindu philosophy, it is the material, efficient, formal and final cause of all that exists. It is the pervasive, genderless, infinite, eternal truth and bliss which does not change, yet is the cause of all changes. Brahman as a metaphysical concept is the single binding unity behind diversity in all that exists in the universe.
Taoism
In Taoism, the Tao is the impersonal principle that underlies reality. It is a metaphysical principle and process that refers to how nature develops, being an enigmatic process of transformation. It is described as the source of existence, an ineffable mystery, and something that can be individually harnessed for the good. It is thought of as being "the flow of the universe" and the source of its order and its qi, but it is not considered a deity to be worshipped, even if some interpretations believed it had the power to bless or illuminate.
Abrahamic religions
Abrahamic conceptions of ultimate reality show diversity, in which some perspectives consider God to be a personal deity, while others have taken more abstract views. John Scotus Eriugena held that God's essence is uncaused and incomprehensible. Similarly, Maimonides believed that God is a perfect unity and is indescribable with positive attributes, and that anthropomorphic imagery in the Bible is metaphorical.
Modern philosophy
Baruch Spinoza believed that God is the natural world, existing eternally and necessarily, and that everything is an effect of God's nature. He defined God as a metaphysical substance rather than a personal being, and wrote in Ethics that "blessedness" comes from the love of God, meaning knowledge of reality as it is.
Contemporary philosophy notes the possibility that reality has no fundamental explanation and should be seen as a brute fact. Adherents of the principle of sufficient reason reject this, holding that everything must have a reason.
Representation
According to Dadosky, the concept of "ultimate reality" is difficult to express in words, poetry, mythology, and art. Paradox or contradiction is often used as a medium of expression because of the "contradictory aspect of the ultimate reality".
According to Mircea Eliade, ultimate reality can be mediated or revealed through symbols. For Eliade the "archaic" mind is constantly aware of the presence of the Sacred, and for this mind all symbols are religious (relinking to the Origin). Through symbols human beings can get an immediate "intuition" of certain features of the inexhaustible Sacred. The mind makes use of images to grasp the ultimate reality of things because reality manifests itself in contradictory ways and therefore can't be described in concepts. It is therefore the image as such, as a whole bundle of meaning, that is "true" (faithful, trustworthy). Eliade says :
the sacred is equivalent to a power, and, in the last analysis, to reality. The sacred is saturated with being. Sacred power means reality and at the same time enduringness and efficacy. The polarity sacred-profane is often expressed as opposition between real and unreal or pseudoreal. [...] Thus it is easy to understand that religious man deeply desires to be, to participate in reality, to be saturated with power.
Common symbols of ultimate reality include world trees, the tree of life, microcosm, fire, children.
Paul Tillich held that God is the ground of being and is something that precedes the subject and object (philosophy) dichotomy. He considered God to be what people are ultimately concerned with, existentially, and that religious symbols can be recovered as meaningful even without faith in the personal God of traditional Christianity.
