76 THEOLOGIANS AND NATURAL PHILOSOPHERS. 



marked the highest point which science reached 

 in Arabia, and the culmination of the encyclopaedic 

 and original studies. Thereafter there was a de- 

 cline in the East, and about the same period there 

 came the inauguration of scientific and philosophi- 

 cal studies in the West. Between 961 and 976 

 scientific works were rapidly imported into Spain, 

 and the interest in these subjects became intense. 

 The three writers from whom we may quote 

 fragments are Avicenna in Arabia, and Avempace 

 and Abubacer in Spain. Draper quotes from Avi- 

 cenna on the origin of mountains, showing that he 

 was a uniformitarian : 



" Mountains may be due to two causes. Either they are effects 

 of upheavals of the crust of the earth, such as might occur during 

 a violent earthquake, or they are the effect of water, which, cut- 

 ting for itself a new route, has denuded the valleys, the strata being 

 of different kinds, some soft, some hard. The winds and waters 

 disintegrate the one, but leave the other intact. Most of the emi- 

 nences of the earth have had this latter origin. It would require 

 a long period of time for all such changes to be accomplished, 

 during which the mountains themselves might be somewhat dimin- 

 ished in size. But that water has been the main cause of these 

 effects, is proved by the existence of fossil remains of aquatic and 

 other animals on many mountains." 



This indicates that a careful search through 

 Arabic natural philosophy would probably yield 

 other evidences of knowledge, not only of the uni- 

 formity of past and present geological changes, but 

 of the gradual development of life. It is unlikely 

 that the Arabs read Aristotle without extending his 



