TUE DEVELOPMENT OF PSYCHOLOGY. 417 



peculiarities in internal structure," has been shown by Mr. Spencer, 

 and is indeed a corollary from the theory of development/ Mr. 

 Bain's method is therefore misleading from its contracted range, but 

 we must here record, as part of our history, its very great advance on 

 the still more incomplete methods of the older psychologists. 



Mr. Bain's other contributions to Psychology are connected with 

 the recent development of one of the sciences whose general method 

 he appropriated. The physiology of the nervous system was of late 

 foundation. Vesalius, Fallopius, Vieussens, Boerhaave, and Willis, had 

 indeed assigned the special functions of certain organs (as those of 

 the senses) to their appropriate nerves, but even in the middle of the 

 eighteenth century the great Haller could deny the existence of any 

 nerve which did not possess the double function of sensation and mo- 

 tion. Whytt and Prochaska, in 1768 and 1800, made observations on 

 reflex and spontaneous movements, and decisively raised the question 

 of the mode of action of the nervous system. In the first quarter of 

 this century Sir Charles Bell established the existence of two great 

 systems of nerves, with difierent functions, and thus revealed a defi- 

 nite mental mechanism. A few years later Dr. Marshall Hall (or some 

 one else) discovered the independent action of the spinal cord, and 

 helped further to determine the organic conditions of mental activity. 

 His contemporary, Miiller, went so far as to assert that the spinal cord 

 was the centre or source of all motor power. At this point IVIr. Bain 

 came into the field. Appropriating the discovery of Hall, he was the 

 first among psychologists to attempt systematically to elucidate the 

 spontaneous movements, as no less a part of the phenomena of mind 

 than those of consciousness. Combining Bell's discovery wdth a hint 

 of Miiller, he introduced the first organic modification into the associa- 

 tion psychology by his theory of the brain as a fountain of force and 

 not merely the passive instrument of impressions. This theory has 

 led him, not only to take into account the secondary mental states 

 generated by the bodily organs, but to trace genetically the origin 

 and growth of voluntary power, and thus to constitute a separate de- 

 partment of Psychology by the analysis of volition, which had pre- 

 viously been the victim of introspection. It has also led him to de- 

 vote a section to " constructive association," which could have no- 

 place so long as there was recognized in the mind no power of origi- 

 nal construction. The tendency to materialize the mental agencies — 

 the assumptions that nerve-force is of the nature of a current, that it 

 moves in diff*used waves, that associations are generated by shocks — 

 are consequences partly of the introduction of the same new elements 

 They are consequences also of that assumed correlation of the mental 

 and nervous with the physical forces which Mr. Bain has, in his later 

 editions, done much to prove and illustrate. 



" If Mr. Herbert Spencer had no other titles to fame, be would 

 ^ " Essays " (second series), p. 125. 



VOL. v.— 27 



