Anaximander, according to Aristotle, was said to explain the persistence of the Earth in its place in the universe on the basis of symmetry. Simplicius however asserted that the Earth was also meant to be supported by air. Although the universe exhibits marked signs of symmetry, it may be assumed that the air under the Earth – in view of its significant cosmological role – really was extended. Anaximander’s conception of a universe of concentrated circles of heavenly bodies, situated around the Earth at their centre, postulated movement of bodies under the Earth as well, in opposition to cosmologies of the time. The orbit of the heavenly bodies under the level of the Earth was, then, conditioned both by their compact structure and by an inclination and demarcation of size and distance. One may, therefore, suppose that Aristotle in reality drew on information referring to Anaximander’s symmetrical universe of circles of heavenly bodies orbiting under the surface of the Earth, which, so it seemed, did not sit on air.