134 THE HISTORY OF CREATION. 



fcrate his attention upon the great problem to which his 

 mind had been turned dming his voyage in the Beagle. In 

 order to show what kind of observations during the voyage 

 principally gave rise to the fundamental idea of the Theory 

 of Selection, and in what manner he afterwards worked 

 it out, I shall insert here a passage from a letter which he 

 addressed to me on the 8th of October, 1864. 



Letter from Charles Darivin to Haechel, Sth October, 1864. 



" In South America three classes of facts were brought 

 strongly before my mind. Firstly, the manner in which 

 closely allied species replace species in going southward. 

 Secondly, the close affinity of the species inhabiting the 

 islands near South America to those proper to the con- 

 tinent. This struck me profoundly, especially the differ- 

 ence of the species in the adjoining islets in the Galopagos 

 Archipelago. Thirdly, the relation of the living Edentata 

 and Rodentia to the extinct species. I shall never forget 

 my astonishment when I dug out a gigantic piece of armour 

 like that of the living armadillo. 



" Reflecting on these facts, and collecting analogous ones, it 

 seemed to me probable that allied species were descended 

 from a common parent. But for some years I could not 

 conceive how each form became so excellently adapted to 

 its habits of life. I then began sj^stematically to study 

 domestic productions, and after a time saw clearly that 

 man's selective power was the most important agent. I was 

 prepared, from having studied the habits of animals, to ap- 

 preciate the struggle for existence, and my work in geology 

 gave me some idea of the lapse of past time. Therefore, 

 when I ha])pened to read " Mai thus on Population," the idea 



