Hesiod and the Pre-Socratics use the Greek term in the context of cosmogony. Hesiod’s Chaos has been interpreted as either “the gaping void above the Earth created when Earth and Sky are separated from their primordial unity” or “the gaping space below the Earth on which Earth rests”.
In Hesiod‘s Theogony, Chaos was the first thing to exist: “at first Chaos came to be” (or was) but next (possibly out of Chaos) came Gaia, Tartarus and Eros (elsewhere the son of Aphrodite). Unambiguously “born” from Chaos were Erebus and Nyx. For Hesiod, Chaos, like Tartarus, though personified enough to have borne children, was also a place, far away, underground and “gloomy”, beyond which lived the Titans. And, like the earth, the ocean, and the upper air, it was also capable of being affected by Zeus’ thunderbolts.
Passages in Hesiod’s Theogony suggest that Chaos was located below Earth but above Tartarus.[15] Primal Chaos was sometimes said to be the true foundation of reality, particularly by philosophers such as Heraclitus.
The notion of the temporal infinity was familiar to the Greek mind from remote antiquity in the religious conception of immortality.[clarification needed] This idea of the divine as an origin[clarification needed] influenced the first Greek philosophers. The main object of the first efforts to explain the world remained the description of its growth, from a beginning. They believed that the world arose out from a primal unity, and that this substance was the permanent base of all its being. Anaximander claims that the origin is apeiron (the unlimited), a divine and perpetual substance less definite than the common elements. Everything is generated from apeiron, and must return there according to necessity. A conception of the nature of the world was that the earth below its surface stretches down indefinitely and has its roots on or above Tartarus, the lower part of the underworld. In a phrase of Xenophanes, “The upper limit of the earth borders on air, near our feet. The lower limit reaches down to the “apeiron” (i.e. the unlimited).” The sources and limits of the earth, the sea, the sky, Tartarus, and all things are located in a great windy-gap, which seems to be infinite, and is a later specification of “chaos”.
In Aristophanes‘s comedy Birds, first there was Chaos, Night, Erebus, and Tartarus, from Night came Eros, and from Eros and Chaos came the race of birds.