154 FROM THE GREEKS TO DARWIN 



A certain unity of type pervades all the different 

 forms of life, like a main type which can display the 

 widest variations. Similarities of external and, still 

 more, of internal, structure pervade all the land ani- 

 mals and are repeated in man. The amphibia, birds, 

 fishes, insects, water animals, depart in widening 

 degrees from this main type, which is lost in the 

 plant and inorganic creation. Our vision reaches no 

 further, but all these transfers render it not im- 

 probable that in the series of extinct forms the same 

 type, in a ruder and simpler form, may have pre- 

 vailed. We can, therefore, assume that, according 

 to their nearness to man, all beings have their 

 greater or less likeness to him, and that the nature 

 of all life seems to conform to a main single plas- 

 ticity of organization. 



We see here that Herder clearly formulated 

 the doctrine of unity of type which prevailed 

 among all the evolutionists of the period immedi- 

 ately following. 



Schelling (1775-1854) 



Friedrich Wilhelm Joseph Schelling at the 

 age of twenty published his Ideen zur einer 

 Philosophie der Natur, Here he first unfolded 

 his ideas of the philosophy of Nature, Kant 

 having spoken of the science of Nature. One 

 section of his philosophy was followed and de- 

 veloped by Oken, but Schelling was greatly 



