E VIDENCES OF E VOL UTION. 91 



On a correct answer to this last all-import- 

 ant question depends, in great measure, the truth 

 or falsity of the theory of organic Evolution. It 

 is a shibboleth which cannot be evaded, a crux 

 which must be explained before an intelligent dis- 

 cussion of the evidences of Evolution is even pos- 

 sible. 



Plato's " Grand Ideas." 



According to Plato, "the world of particular 

 things is somehow determined by preexisting uni- 

 versal ideas." Species and genera, therefore, are but 

 expressions of the ideas of the Creator ; and classifi- 

 cations of animals and plants, according to types, 

 are but translations of the thoughts of God ; expres- 

 sions of grand ideas which from all eternity have 

 been before the Divine mind. Types, then, are but 

 the copy ; the Divine ideas, the pattern or arche- 

 type. Species, as Plato conceived them, were im- 

 mutable, and organic Evolution, as now understood, 

 was, accordingly, impossible. 



During the Middle Ages, Plato's doctrine of 

 types was accepted without question, and species 

 were looked upon as being as immutable as the 

 rules of dialectics, as unchangeable as truth itself. 

 Thus the great Scotus Erigena, probably the 

 profoundest philosopher of his time, declares that 

 " that art which divides genera into species, and re- 

 solves species into genera, which is called dialectics, 

 is not the product of human ingenuity, but has its 

 origin in the nature of things and is due to the 

 Author of all arts which are true arts, and has been 



