EIGHTEENTH CENTURY EVOLUTIONISTS 171 



cles with a sort of rudimentary sensibility, which 

 impels them to constantly change their position 

 in search of the most favorable position — a form 

 of the attraction and repulsion doctrine of Em- 

 pedocles applied to organic particles: 



The animal is a sj^stem of different organic mole- 

 cules, which, impelled by sensations similar to those 

 of obtuse and vague touch — sensations which have 

 been imparted to them by Him who created matter 

 in general — have combined, until each has found the 

 position most suitable to its form and to its repose. 



This position, says Perrier, may be changed by 

 the innumerable disturbances caused by an ac- 

 cess of new particles which have not yet obtained 

 their repose. 



Diderot proceeds by asking whether plants and 

 animals have always been what they now are; 

 then, continuing in a spirit similar to that of Des- 

 cartes, he revives the Anaxagorean doctrine of 

 pre-existent germs in a modified form: 



Even if Revelation teaches us that species left the 

 hands of the Creator as they now are, the philosopher 

 who gives himself up to conjecture comes to the con- 

 clusion that life has always had its elements scattered 

 in the mass of inorganic matter ; that it finally came 

 about that these elements united; that the embryo 

 formed of this union has passed through an infini- 

 tude of organization and development; that it has 

 acquired, in succession, movement, sensation, ideas. 



