THE DEVELOPMENT OF PSYCHOLOGY. 301 



doubtful. The literature of the day was drenched with metaphors 

 taken from the dominant science. Fashion, after a long interval, once 

 more patronized Nature, and the *' bottle-and-squirt mania " spread. 

 Experimentalism in Psychology was still under a cloud, from the dis- 

 credit which had attached to the premature theorizing of Hartley. 

 But in the early part of the century, Dr. Thomas Brown had gained a 

 hearing, under cover of the respectable orthodoxy of the Scotch uni- 

 versities, for speculations thickly sown with revolutionary germs. 

 One of his pupils was James Mill, and in 1829 that resolute and thor- 

 ough-going, if narrow and aggressive, thinker published the treatise 

 w^hich marked the turn of the tide. Deriving his inspiration from the 

 neglected work of Hartley, gathering up the hints freely scattered in 

 Brown's lectures, and imbued with the spirit of the prevailing chemis- 

 try, he set about constructing a new science of mind, of which the 

 physics should not be obsolete, and which should push the analysis of 

 the accepted metaphysical mysteries to the farthest possible limit. He 

 obeyed the double analytic and synthetic movement in contemporary 

 chemical investigation. As specimens of his analytical advance, we 

 may point to his further resolution of the apparently simple ideas of 

 hardness and extension, which had been begun by Hartley and con- 

 tinued by Darwin.^ But, as better illustrating the dynamical influ- 

 ence of physical science, we prefer to lay emphasis on what may, as 

 it appears to us, be justly styled his synthetical contribution to Psy- 

 chology. This was his conception, applied to the whole range of 

 mental phenomena, of the chemical nature of association. Quite to 

 realize the new shape which the welding mental power took in his 

 hands, we must glance back at its history. It is comparatively young. 

 Hobbes knew nothing of it : his " synthesis," by which things are 

 " constructed or generated," is purely geometrical,' and with him as- 

 sociation is mere sequence.^ Locke's advance on this is clear, though 

 inconsiderable : he speaks of the " tying together of ideas," and de- 

 scribes certain ideas as appearing in "gangs, always inseparable,"^ but 

 he regards " mixed modes" as made by men voluntarily with a view 

 to communication.^ Hartley, according to Mr. J. S. Mill, had reached 

 the stage we have above stated as only attained by James Mill : 



"It was reserved for Hartley to show that mental phenomena, joined to- 

 gether by association, may form a still more intimate, and as it were chemical 

 union; . . . the compound Laving all the appearance of a phenomenon sui generis, 

 as simple and elementary as the ingredients, and with properties diiferent from 

 any of them." ® 



This is far too strongly stated. That the union of the associated 

 mental elements as conceived by Hartley was more intimate than their 

 mode of conjunction as conceived by Locke, or their rigidity of sequence 



1 "Analysis," i., 92. 2 "Elements of Philosophy," i., pp. 812, 313. 



3 " Human Nature," ch. iv. * " Essay," book ii., ch. xxxiii. 



5 "Ibid., ch. xxii. ^ "Dissertations," iii., 108. 



