250 DARWIN. 



individuals, or as a ' variety ' in modern terms. This 

 we have seen originate with Empedocles and receive 

 the support of Epicurus and Lucretius, and much 

 more recently of Hume, Diderot, and others. In 

 its relation to modern Evolution, we see it brought 

 out afresh by Buffon, Malthus, Kant, Wells, Mat- 

 thew, and Wallace. The second line is the survival 

 of certain types, because of the possession of some 

 fortuitously adaptive combination of parts or of 

 some favourable variation in a single organ. This 

 conception we also trace from Diderot back to 

 Empedocles ; but it is apparently a spontaneous 

 and independent discovery as we find it in Buffon 

 and Helvetius, who transmit it to Erasmus Darwin. 

 Finally, it is again rediscovered, or grandly evolved 

 by induction and observation by Charles Darwin, 

 who raises it to its present magnitude as a central 

 principle in the living world. 



An entirely distinct line of thought is that of 

 Erasmus Darwin and of Lamarck that life itself is 

 a process of adaptation to new conditions and that 

 the adaptive changes acquired in course of life are 

 transmitted and accumulated in successive genera- 

 tions. This is a theory for adaptations of certain 

 kinds which awaits further proof. 



It is also for the future to determine whether 

 the predecessors of Darwin and Darwin himself, in 

 the principle to which he gave a life of thought, 

 have fully answered the old, old problem, or whether 

 we shall look for still another Newton in our phi- 

 losophy of Nature. 



