30 CELESTIAL, ATMOSPHERIC, AND 



of a statue then it will exist in that form.* The infinite can 

 exist only as an object of contemplation, but the capability 

 of division without end gives to the potential infinite some 

 kind of actual existence.! The upper parts of the Kosmos 

 are full of Eether, which is of such a nature that it is always 

 moving in a circular path, and, being of this nature, it can- 

 not have either heaviness or lightness ; further, it was not 

 generated and could not be destroyed, being incapable of 

 change, quantitative or qualitative.! It was of this element 

 that Aristotle believed the heavenly bodies to consist. § He 

 says that some believed that the stars were of fire, but it 

 should be understood that they were not, nor were they 

 carried round in a medium of fire.H In his De Coelo, ii. cc. 

 7 and 8, he speaks of the Sun and Stars being fastened 

 {bhhlxzvQs) in the Heavens. This seems at first sight difficult 

 to understand, suggesting as it does the necessity of sup- 

 porting almost incalculable masses, but Aristotle's assumption, 

 previously referred to, that the heavenly bodies are of aether, 

 which has neither heaviness nor lightness, would remove 

 any difficulty of this kind. His ideas about the fixing of the 

 heavenly bodies in the Heavens were borrowed, in part at 

 least, from earlier philosophers, especially Pythagoras and 

 Parmenides. 



Beneath the higher parts of the Kosmos, filled with aether, 

 was the zone, if it may be so called, of fire, which Aristotle 

 supposed to be between the osther and the air, beneath 

 which were water and earth. ^ In the zone of fire, however, 

 he contemplated the presence of a dry, earthy exhalation, 

 to be referred to later, and of air, probably in the same way 

 that he recognized the presence of watery vapour in the air. 



Having set out, so far, his views on the stars and other 

 heavenly bodies, Aristotle's explanations of the way in which 

 the heat and light of these bodies is caused will be considered. 

 Many difficulties arise in the mind of anyone reading through 

 his statements on this subject, chiefly in his De Coelo, ii. c. 7, 

 but his explanation may be expressed as follows : — Obser- 

 vations on the motion of missiles show that they become 

 highly heated or are even ignited, and, he adds, the air is 

 similarly affected. Since, then, heat is produced by the 



''■' Physics, iii. c. 6. s. 2. 



f De Gener. et Corr. i. c. 3, 318a ; MetapJiys. viii. c. G, 10486. 



I De Ccelo, i. c. 2, 2696, i. c. 3, 2696 and 270<z; Meteorol. i. c. 3, s. 4. 



§ Meteorol. i. c. 2, p. 1 ; De Ccelo, ii. c. 7, 289rt; ; De Miindo, c. 2, 392. 



il De Ccelo, ii. c. 7. IT Meteorol. i. c. 3, s. 14 ; De Coelo, ii. c. 4, 287rt. 



