DARWIN AND HIS REVIEWERS. 163 



greater part of physical inquiries now relate to mo- 

 lecular actions, which, a distinguished natural philoso- 

 pher informs us, " we have to regard as the results of 

 an infinite number of infinitely small material parti- 

 cles, acting on each other at infinitely small distances " 

 — a triad of infinities — and so physics becomes the 

 most metaphysical of sciences. Verily, if this style of 

 reasoning is to prevail — 



" Thinking is but an idle waste of thought, 

 And naught is everything, and everything is naught." 



The leading objection of Mr. Agassiz is likewise of 

 a philosophical character. It is, that species exist only 

 " as categories of thought " — that, having no material 

 existence, they can have had no material variation, and 

 no material community of origin. Here the predica- 

 tion is of species in the subjective sense, the inference 

 in the objective sense. Reduced to plain terms, the 

 argument seems to be : Species are ideas ; therefore 

 the objects from which the idea is derived cannot vary 

 or blend, and cannot have had a genealogical connec- 

 tion. 



The common view of species is, that, although they 

 are generalizations, yet they have a direct objective 

 ground in Nature, which genera, orders, etc., have not. 

 According to the succinct definition of Jussieu — and 

 that of Linnaeus is identical in meaning — a species is 

 the perennial succession of similar individuals in con- 

 tinued generations. The species is the chain of which 

 the individuals are the links. The sum of the genea- 

 logical! y-connected similar individuals constitutes the 

 species, which thus has an actuality and ground of dis- 



