The Doctrine of Evolution. 453 



a progressive differentiation and integration of such corre- 

 spondences. Intellectual life is shown to have arisen by 

 slow gradations, and the special interpretations of reflex 

 action, instinct, memory, reason, emotion, and will are such 

 as to make the Principles of Psychology indubitably the 

 most suggestive book upon mental phenomena that was ever 

 written. 



Toward the end of the first edition of the Origin of Spe- 

 cies, published in 1859, Mr. Darwin looked forward to a 

 distant future when the conception of gradual development 

 might be applied to the phenomena of intelligence. But 

 the first edition of the Principles of Psychology, in which 

 this was so successfully done, had already been published 

 four years before in 1855 so that Mr. Darwin in later 

 editions was obliged to modify his statement and confess 

 that, instead of looking so far forward, he had better have 

 looked about him. I remember hearing Mr. Darwin laugh 

 merrily over this at his own expense. 



This extension of the doctrine of evolution to psychical 

 phenomena was what made it a universal doctrine, an ac- 

 count of the way in which the world, as we know it, has 

 come to be. There is no subject great or small that has not 

 come to be affected by the doctrine, and, whether men re- 

 alize it or not, there is no nook or corner in speculative sci- 

 ence where they can get away from the sweep of Mr. Spen- 

 cer's thought. 



This extension of the doctrine to psychical phenomena 

 is by many people misunderstood. The Principles of Psy- 

 chology is a marvel of straightforward and lucid statement ; 

 but, from its immense reach and from the abstruseness of 

 the subject, it is not easy reading. It requires a sustained 

 attention such as few people can command except on sub- 

 jects with which they are already familiar. Hence few 

 people read it in comparison with the number who have 

 somehow got it into their heads that Mr. Spencer tries to 

 explain mind as evolved out of matter, and is therefore a 

 materialist. How many worthy critics have been heard to 

 object to the doctrine of evolution that you can not deduce 

 mind from the primeval nebula, unless the germs of mind 

 were present already ! But that is just what Mr. Spencer 

 says himself. I have heard him say it more than once, and 

 his books contain many passages of equivalent import.* He 



* See, for example. Principles of Psychology, second edition, 1870- "72, vol. ii, 

 pp. 145-102. 



