that the many hippopotamus bones found in Sicily were 

 remains of human giants, in comparison with which the pres- 

 ent race were as children. Here, he thought, was a battle 

 held between the gods and the Titans, and the bones belonged 

 to the slain. Pythagoras (582 B. C.) had already anticipated 

 one conclusion of modern geology, if the following statement, 

 attributed to him by Ovid, was his own :* 



Vidi ego quod fuerat solidissima tellus, 

 Esse fvetum : vidi factas ex sequore terras ; 

 Et procul a pelago conchas jacuere marinse. 



Aristotle (384-322 B. C.) was not only aware of the exist- 

 ence of fossils in the rocks, but has also placed on record saga- 

 cious views as to the changes in the earth's surface necessary 

 to account for them. In the second book of his Meteorics, he 

 says : " The changes of the earth are so slow in comparison to 

 the duration of our lives, that they are overlooked ; and the 

 migrations of people after great catastrophes and their removal 

 to other regions, cause the event to be forgotten." Again, in 

 the same work, he says : " As time never fails, and the universe 

 is eternal, neither the Tanais, nor the Nile, can have flowed 

 for ever. The places where they rise were once dry, and there 

 is a limit to their operations : but there is none to time. So 

 of all other rivers ; they spring up, and they perish ; and the 

 sea also continually deserts some lands and invades others. 

 The same tracts, therefore, of the earth are not, some always 

 sea, and others always continents, but everything changes in 

 the course of time." 



Aristotle's views on the subject of spontaneous generation 

 were less sound, and his doctrines on this subject exerted a 

 powerful influence for the succeeding twenty centuries. In 

 the long discussion that followed concerning the nature of 

 fossil remains, Aristotle's views were paramount. He believed 

 that animals could originate from moist earth or the slime of 

 rivers, and this seemed to the people of that period a much 

 * Metamorphoses, Liber XV, 262. 



