hills and ravines. He took as his principles the homoeomeries or homogeneous molecules ; for just as gold consists of fine particles which are called gold-dust, so he held the whole universe to be compounded of minute bodies having parts homogeneous to themselves. His moving principle was Mind ; of bodies, he said, some, like earth, were heavy, occupying the region below, others, light like fire, held the region above, while water and air were intermediate in position. For in this way over the earth, which is flat, the sea sinks down after the moisture has been evaporated by the sun. In the beginning the stars moved in the sky as in a revolving dome, so that the celestial pole which is always visible was vertically overhead ; but subsequently the pole took its inclined position. He held the Milky Way to be a reflection of the light of stars which are not shone upon by the sun; comets to be a conjunction of planets which emit flames; shooting-stars to be a sort of sparks thrown off by the air. He held that winds arise when the air is rarefied by the sun’s heat ; that thunder is a clashing together of the clouds, lightning their violent friction; an earthquake a subsidence of air into the earth. Animals were produced from moisture, heat, and an earthy substance; later the species were propagated by generation from one another, males from the right side, females from the left. There is a story that he predicted the fall of the meteoric stone at Aegospotami, which he said would fall from the sun.* Hence Euripides, who was his pupil, in the Phaéthon calls the sun itself a “ golden clod.” ® Furthermore, when he went to Olympia,