58 Edward Livingston Youmafis. 



of the public for half a century by the French school, and 

 are supported only by antiquated assertions, and by no 

 means by facts scientifically ascertained. It must be owing 

 to some particular circumstance that this work has been so 

 much noticed, because really it is not worthy of critical 

 examination by a serious scientific man. 



This criticism of The Vestiges is in the main cor- 

 rect and well deserved ; yet I suspect that Youmans 

 already felt that somewhere in all that heap of chaff 

 there was a sound and sturdy kernel of truth. Sir 

 Charles Lyell had in 1830 shown how enormous geo- 

 logic effects are wrought by the cumulative action 

 of slight and unobtrusive causes ; and this, which had 

 so much to do with turning men's minds toward some 

 conception of evolution, was not without its effect 

 upon Youmans. Full illustrated reports of Agassiz's 

 lectures were published in the Tribune, and were read 

 and re-read to him and carefully pondered ; and from 

 this time the tendency of his thinking was more and 

 more tow^ard the development theory.* 



The project for a history of progress in discovery 

 and invention had been suggested by the dates in 

 Goureaud's mnemotechnical system. Eschewing the 

 dfeeds of popes, kings, and emperors, the dates of 

 sieges, battles, and massacres, Youmans was intent on 

 weaving into a connected story the triumphs of ob- 

 servers, explorers, experimenters, and philosophers. 

 At once brother and sister began the work of gather- 



* In this connection I can not refrain from adding that in my own case 

 the immediate cause which drove me to the development theory was the 

 mental reaction experienced in reading Agassiz's arguments against that 

 theory in his Essay on Classification, in 1859, shortly before Darwin's book 

 was published. 



