Greek

 Anaximander (c. 610 – c. 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.