118 A Century of Science 



about that. It was certainly of great significance 

 that the particular race of mammals whose intelli- 

 gence increased far enough to make it worth while 

 for natural selection to work upon intelligence alone 

 was the race which had developed hands and could 

 manipulate things. It was a wonderful era in the 

 history of creation when that creature could take 

 a club and use it for a hammer, or could pry up a 

 stone with a stake, thus adding one more lever to 

 the levers that made up his arm. From that day 

 to this, the career of man has been that of a person 

 who has operated upon his environment in a differ- 

 ent way from any animal before him. An era of 

 similar importance came probably somewhat later, 

 when man learned how to build a fire and cook his 

 food ; thus initiating that course of culinary de- 

 velopment of which we have seen the climax in our 

 dainty dinner this evening. Here was another 

 means of acting upon the environment. Here was 

 the beginning of the working of endless physical 

 and chemical changes through the application of 

 heat, just as the first use of the club or the crow- 

 bar was the beginning of an enormous development 

 in the mechanical arts. 



Now, at the same time, to go back once more 

 into that dim past, when ethics and religion, 

 manual art and scientific thought, found expres- 



