De Incredibilibus (excerpta Vaticana)

Likewise, it is said that Phaethon was the son of Helius. But here is how it was. Phaethon calculated the course of the sun, as Endymion did with the moon, but these calculations were not precise and he died leaving his account incomplete.

Bellerophon’s horse was not winged, as in the myth. Rather, by pursuing astronomy, turning his thoughts to higher things and wandering amongst the stars he went up to the heavens not on a horse but by using his mind.