48 A Century of Science 



of the Spenceriaii world as it was the centre of the 

 world of mediaeval theology ; and the history of 

 the evolution of conscious intelligence becomes a 

 theme of surpassing interest. 



This is the part of his subject which Mr. Spen- 

 cer has handled in the most masterly manner. 

 Nothing in the literature of psychology is more re- 

 markable than the long- sustained analysis in which 

 he starts with complicated acts of quantitative rea- 

 soning and resolves them into their elementary 

 processes, and then goes on to simpler acts of 

 judgment and perception, and then down to sensa- 

 tion, and so on resolving and resolving, until he 

 gets down to the simple homogeneous psychical 

 shocks or pulses in the manifold compounding and 

 recompounding of which all mental action consists. 

 Then, starting afresh from that conception of life as 

 the continuous adjustment of inner relations within 

 the organism to outer relations in the environment, 

 a conception of which he made such brilliant 

 use in his " Principles of Biology," he shows 

 how the psychical life gradually becomes special- 

 ized in certain classes of adjustments or correspond- 

 ences, and how the development of psychical life 

 consists in a progressive differentiation and inte- 

 gration of such correspondences. Intellectual life 

 is shown to have arisen by slow gradations, and 



