116 FROM THE GREEKS TO DARWIN 



such as might occur during a violent earthquake, or 

 they are the effect of water, which, cutting for itself 

 a new route, has denuded the valleys, the strata be- 

 ing of different kinds, some soft, some hard. The 

 winds and waters disintegrate the one, but leave the 

 other intact. Most of the eminences of the earth have 

 had this latter origin. It would require a long period 

 of time for all such changes to be accomplished, dur- 

 ing w^hich the mountains themselves might be some- 

 what diminished 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 evolution of life. It is unlikely 

 that the Arabs read Aristotle without extending 

 his theory of the origin of life to their wide sur- 

 vey of Nature. 



We take from Guttler the following passages 

 regarding the Spanish philosophers: 



The Arabic philosophers in Spain threw into a 

 stronger light the natural connection between the in- 

 organic and the organic world. In Avempace's (Ibn- 

 Badja) treatise there are said to exist between men, 

 animals, plants, and minerals, strong relations which 

 bind them into a single and united whole. Through 



