62 SCIENCE IN GRECO-ROMAN ANTIQUITY 



he does not appear to have understood the interest of 

 higher mathematics. The ideas of function, and of 

 geometrical loci were unknown to him ; on this point 

 he was inferior to Plato. 1 With the help of the 

 astronomer Calippus, Aristotle attempted to perfect 

 the system of Eudoxus by introducing compensating 

 spheres so as to give solidarity to the movements of 

 the planets and of the celestial vault. He was also 

 interested in meteorological phenomena. In his eyes 

 it is heat which plays the most important part ; it 

 contributes to the formation of comets, the Milky Way, 

 clouds, winds, etc. The rainbow is only a phenomena 

 of reflection, the droplets of the cloud acting as mirrors 

 to the sunlight. {Meteor., Bk. Ill, ch. iv. ; 373 to 

 32.) Aristotle approaches physics as a theorist and 

 a metaphysician ; he discusses carefully ideas of 

 place, motion, etc., but very often interprets pheno- 

 mena erroneously, although he was on the point 

 of discovering specific gravity. With Plato, he adds 

 to the four known elements a fifth, the quintessence. 

 By his ideas, he has, up to a certain point, impeded 

 the progress of physics ; on the other hand he exercised 

 a happy influence on the evolution of alchemy and 

 consequently of chemistry. The collection of writings 

 entitled Problems shows us the extent and variety of 

 the instruction which was given in the Peripatetic 

 School, for it deals with medicine, physiology, mathe- 

 matics, optics, music, philology, etc. In this collec- 

 tion the mechanical problems are particularly remark- 

 able, because side by side with palpable errors there 

 are glimpses of the most important laws of mechanics 

 (the principle of virtual velocities, parallelogram of 

 forces, law of inertia, use of tackle). The influence of 

 the investigations of Archytas can be seen here. 2 But, 

 as we have already remarked, Aristotle was, before all, 



1 21 Milhaud, Etudes, p. 101 et seq. 



2 15 Heiberg, Naturwiss., p. 35. 



