There are, we are told, seven planets amongst these luminaries, and these move in a direction opposite to that of the heaven: hence the name planets. For, while they say that the heaven moves from east to west, the planets move from west to east; but the heaven bears the seven planets along with it by its swifter motion. Now these are the names of the seven planets: Luna, Mercury, Venus, Sol, Mars, Jupiter, Saturn, and in each zone of heaven is, we are told, one of these seven planets: