The essay considers synthetically the passages of Hesiod’s Theogony concerning Khaos, Gaia, Uranòs, and Tàrtaros as describing the cosmic structure at its very beginning and at its present state. The final result of the cosmogenetic process consists of three solid parallel disks of equal size separated from one another by the space of Khaos/Aèr. The whole structure is conceived of as an ideal cylinder, whose superior base is Uranòs, the inferior one is Tàrtaros and the median section is Gaia, dividing (...) the whole cylinder into two high semicylinders full of Khaos/Aèr. From this Khaos/Aèr, the primal Four Elements derive, as plants do from their roots, from which all other substances of the universe originate in turn. Thus, Khaos is arkhè not only in the chronological-historical sense, but also in the sense of an eternal generative substance of all things. We may conclude that the Hesiodic word khaos is a lexical ancestor of the later physical and philosophical term hyle because it conveys the primeval notion of ‘matter’. (shrink)