NATURAL PHILOSOPHERS. 87 



says St. Hilaire, " the foundation of Microscopy ; 

 Anatomy enriched and joined to Physiology ; Com- 

 parative Anatomy studied with care ; Classification 

 placed on a rational and systematic basis." It was 

 these sciences and especially the rise of clearer ideas 

 on the nature of species, which first gave specu- 

 lation upon Evolution its modern trend, bringing 

 up the origin and the mutability of species as two 

 great central questions. 



During these two progressive centuries there 

 were three classes of writers who contributed more 

 or less directly to the foundations of modern Evo- 

 lution, before its open exposition by Buffon. First, 

 the Naturalists, among whom few speculative 

 questions were in vogue, were nevertheless really 

 building up the future materials of thought. Second, 

 the Speculative Evolutionists, who gave a free 

 rein to thoroughly unsound ideas upon the origin 

 of species and preserved many of the early Greek 

 notions. Finally, there were the great Natural 

 Philosophers, such as Bacon, Descartes, Leibnitz, 

 Hume, ending with the later German school, Kant, 

 Lessing, Herder, and Schelling. 



It is a very striking fact, that the basis of our 

 modern methods of studying the Evolution prob- \ 

 lem was established not by the early naturalists 

 nor by the speculative writers, but by the Philos- 

 ophers. They alone were upon the main track of 

 modern thought. It is evident that they were 

 groping in the dark for a working theory of the 



