44 SCIENCE IN GRECO-ROMAN ANTIQUITY 



but being accused of atheism for having said that the 

 heavenly bodies were simple material bodies, even the 

 friendship and protection of Pericles could not save him 

 from banishment, and he took refuge at Lampsacus, 

 where he died in 428 B.C., honoured by all for the no- 

 bility of his character. He left a " Treatise on Nature," 

 several fragments of which have come down to us. In 

 this treatise he is the first to give the true explanation of 

 the phases of the moon, likewise the first to discover the 

 true nature of the light of the moon, and consequently 

 he expounds the theory of eclipses. On the other hand, 

 he considers the sun, moon, and all the stars to be burn- 

 ing stones, which are moved in a circle by the rotation 

 of the ether. Unfortunately, on other points, he holds 

 the opinions of Anaximenes, and regards the earth as a 

 flat and concave body. As to the universe, Anaxagoras 

 declares that it is at one and the same time infinite and 

 animated by a movement of diurnal rotation, and in 

 order to remove the contradiction implied by this 

 affirmation, he admits that one part only of the universe 

 is in motion, and, with the exception of this part, all 

 that extends to the infinite is motionless. Motion is 

 not inherent in matter, it is communicated to it from 

 without by means of a subtle and intelligent fluid which 

 is Mind or Nous (vovg) . This is not the supreme intelli- 

 gence, in the meaning which Plato and Aristotle give to 

 this term. It is rather an organizing omniscient force, 

 which is at the same time corporeal, personal and im- 

 personal, and which relates more to the physical order 

 than to the moral order (Plato : Phaedo, 97 c). 

 This being so, the universe is formed as follows : The 

 Nous puts in motion a portion of the infinite and 

 immobile matter, then it propagates its organizing 

 influence over a vaster and vaster region of the universe. 

 No limit can be assigned to this influence, since on one 

 hand the universe is indefinitely extended, and on the 

 other hand matter is indefinitely divisible, for vacuum 



