Of the stars some are fixed, and are carried round with the whole heaven; others, the wandering stars or planets, have their special motions. The sun travels in an oblique path through the zodiac. Similarly the moon travels in a spiral path. The sun is pure fire : so Posidonius in the seventh book of his Celestial Phenomena. And it is larger than the earth, as the same author says in the sixth book of his Physical Discourse. Moreover it is spherical in shape like the world itself according to this same author and his school. That it is fire is proved by its producing all the effects of fire ; that it is larger than the earth by the fact that all the earth is illuminated by it ; nay more, the heaven beside. The fact too that the earth casts a conical shadow proves that the sun is greater than it. And it is because of its great size that it is seen from every part of the earth. The moon, however, is of a more earthy composition, since it is nearer to the earth. These fiery bodies and the stars generally derive their nutriment, the sun from the wide ocean, being a fiery kindling, though intelligent ; the moon from fresh waters, with an admixture of air, close to the earth as it is : thus Posidonius in the sixth book of his Physics ; the other heavenly bodies being nourished from the earth. They hold that the stars are spherical in shape and that the earth too is so and is at rest ; and that the moon does not shine by her own light, but by the borrowed light of the sun when he shines upon her. An eclipse of the sun takes place when the moon parses in front of it on the side towards us, as shown by Zcno with a diagram in his treatise On the Whole. For the moon is seen approaching at conjunctions and