-630 THE BEGINNINGS OF LIFE. 



thousand centuries. We know positively that he was 

 contemporaneous with many now extinct animals, and 

 has survived changes of the earth's surface fifty or a 

 hundred times greater than any that have occurred 

 during the historical period ; but we cannot place any 

 definite limit to the number of species he may have 

 outlived, or to the amount of terrestrial change he may 

 have witnessed. 5 



Mr. Wallace has, moreover, adduced a number of 

 very cogent reasons for believing that such creatures 

 as the ancestors of man must have been, would, at a 

 certain stage in their history, have ceased to undergo any 

 notable variations in external conformation, although 

 a steady progress might continue to take place in the 

 developmental organization of the brain, leading to 

 a progressive increase of mental power. He says 1 : 

 c From the moment when the first skin was used as 

 a covering, when the first rude spear was formed to 

 assist in the chase, when fire was first used to cook his 

 food, when the first seed was sown or shoot planted, 

 a grand revolution was effected in nature, a revolution 

 which in all the previous ages of the eaitrr's history had 

 had no parallel; for a being had arisen who was no 

 longer necessarily subject to change with the changing 

 universe a being who was in some degree superior to 

 nature, inasmuch as he knew how to control and regu- 

 late her action, and could keep himself in harmony 

 with her, not by a change in body, but by an advance 

 1 Loc. cit, pp. 325 and 317. 



