CH. XIV.] LIFE AND MIND. 83 



objective psychology and of nervous physiology ; we need 

 to compare the mental processes observed in adult civilized 

 men, with the mental processes observed or inferred in 

 civilized children, in adult barbarians, and in the lower 

 animals, down to those humble organisms in which the phe- 

 nomena of intelligence first become differentiated from the 

 phenomena of organic life. The immense advance which haa 

 been made in mental science during the past forty years, has 

 been mainly due to the practical recognition of this fact. 

 Treatises on psychology are no longer solely based upon an 

 analysis of what happens when " I see the inkstand," 

 although analyses of this sort are still, as is here maintained, 

 indispensable. The nervous system, in its ascending com- 

 plications from the amphioxus to man, is now taken into 

 the account. The normal variations in psychical manifes- 

 tation, in the various human races, from childhood to old 

 age, are taken into the account. The abnormal variations 

 caused by stimulknts and narcotics, as well as those ex- 

 hibited in epilepsy, insanity, and other forms of nervous 

 disease, are taken into the account. And careful investi- 

 gations into the ways in which different organisms respond 

 to external stimuli, show us that the lower forms of psy- 

 chical activity are no longer neglected. While the analysis 

 of complex mental operations has been pushed to an extent 

 which until lately would have been deemed impracticable, 

 on the other hand the sub-science of psychogeny, dealing 

 with the origin of the various manifestations of mental 

 activity, has arisen to coordinate importance with subjective 

 )sychology. It has become generally recognized that — in- 

 ffaceable as is the distinction between the phenomena of 

 consciousness and all other phenomena — nevertheless the 

 one as well as the other can be scientifically explained, 

 only when present manifestations are studied in their con- 

 nection with past manifestations. In this domain, as in 

 all others, the Law of Evolution holds sway. 



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