Tried and convicted of impiety in an Athenian court, Anaxagoras spent the remaining years of his life in exile. The following passage (from the third-century C.E. theologian Hippolytus) records some of the theories that might well have provided the prosecution with ammunition for its case against the philosopher.

The earth (he thinks) is flat in shape," and stays suspended from where it is because of its size, because there is no void and because the air, which is very strong, keeps the earth afloat on it. . . . The sun, the moon, and all the stars are red-hot stones which the rotation of the aither carries round with it. Beneath the stars are certain bodies, invisible to us, that are carried around with the sun and moon. We do not feel the heat of the stars because they are so far from...