Arche
Arche (Ancient Greek: ἀρχή) is a Greek word with primary senses "beginning", "origin" or "source of action". (εξ’ ἀρχής: from the beginning, οr εξ’ ἀρχής λόγος: the original argument), and later first principle or element, first so used by Anaximander (Simplicius in Ph. 150.23), principles of knowledge (ἀρχαί) (Aristot. Metaph. 995b8). By extension, it may mean "first place, power", "method of government", "empire, realm", "authorities" (in plural: ἀρχαί), "command". The first principle or element corresponds to the "ultimate underlying substance" and "ultimate undemonstrable principle". In the philosophical language of the archaic period (8th-6th century BC), arche (or archai) designates the source, origin or root of things that exist. In ancient Greek philosophy, Aristotle foregrounded the meaning of arche as the element or principle of a thing, which although undemonstrable and intangible in itself, provides the conditions of the possibility of that thing.
Mythical cosmogonies
In the mythical Greek cosmogony of Hesiod (8th-7th century BC), the origin of the world is Chaos, considered as a divine primordial condition, from which everything else appeared. In the creation "chaos" is a gaping-void, but later the word is used to describe the space between the earth and the sky, after their separation. "Chaos" may mean infinite space, or a formless matter which can be differentiated. The notion of temporal infinity was familiar to the Greek mind from remote antiquity in the religious conception of immortality. The conception of the "divine" as an origin, influenced the first Greek philosophers.