164 SCIENCE IN GRECO-ROMAN ANTIQUITY 



are the stars. According to Anaximander, they result 

 from the partial or total obstruction of the opening of 

 the felloes. Anaximenes explains them by the inter- 

 vention of earthy dark bodies which move around the 

 celestial vault. Empedocles, however, knew the true 

 theory of the solar eclipses, though it was Anaxagoras 

 who clearly formulated it, as Hippolytus reports : 

 " The moon is eclipsed by the earth which robs it of 

 the light of the sun, and also sometimes by the bodies 

 which are below it and pass in front of it. The sun is 

 eclipsed at new moon, when the moon hides it from us." 

 (Diels, Vor. I, 301, 47.) 



As to the shape and position of the earth, the first 

 Ionians generally considered this as a cylinder sup- 

 ported by water or suspended in the air, or as a thin 

 disc, or again as a dish with turned-up edges. 

 Pythagoras seems to have been the first to affirm the 

 sphericity of the earth, which was distinctly proclaimed 

 by Parmenides. 1 



Finally, it may be said that the conceptions of the 

 comparative movements of the heavenly bodies are 

 lacking in precision, and vary according to their authors. 

 These all agree that the region of the fixed stars accom- 

 plishes a revolution round the celestial pole in 24 hours ; 

 but they differ in their views regarding the sun, moon 

 and planets. These heavenly bodies are sometimes re- 

 garded as meteors which traverse the atmosphere by 

 an independent motion, sometimes as bodies partially 

 drawn by the movement of revolution of the starry 

 heaven. 



2. THE PHYSICAL HYPOTHESES 



The Pythagorean school did not entirely abandon 

 the meteorological studies of its predecessors, but it 

 added to them the desire to comprehend the mechanism 



1 25 Tannery, Science helUne, p. 208. 



