THE POPULAR SCIENCE MONTHLY. 



THE DEYELOPME^^T OF PSYCHOLOGY. 



THE progress of Psychology has been determined by agencies 

 which may, with much precision, be discriminated as two sets 

 of conflicting yet cooperating forces — those maintaining equilibrium, 

 and those producing motion. This language would be justly con- 

 demned as mechanical if it in any degree presupposed the vulgar no- 

 tion of force, as acting on visible masses of matter and causing sen- 

 sible motion. But since vital, mental, and even social phenomena, as 

 well as the oscillations of molecules and tlie ethereal undulations, are 

 now alike interpreted in terms of mechanism, we may reasonably 

 claim that the phraseology shall receive the greatest latitude of inter- 

 pretation consistent with the admission of no mechanical assumptions. 

 If, wath more propriety, it be censured as scholastic, as raising mere 

 observed uniformities into self-acting entities, it may be replied that 

 the term force is scholastic only when used scholastically, that it has 

 a true and unmistakable meaning as a generalization simply, and that 

 progress of all kinds can be best described in the language of the sci- 

 ence which has clothed the laws of the action of force with the great- 

 est possible precision and certainty. Under these reservations, we 

 use no mere metaphor in describing the development of Psychology 

 as due to two sets of forces, which may be styled kinetical and stati- 

 cal respectively, according as their function has been to produce ex- 

 ternal change or to effect those internal readjustments which previous 

 changes had rendered necessary. 



The statical factor in psychological history is Theology. The 

 mother of all the sciences, it gives birth to Psychology first of the 

 sciences of mind; all the great problems, the discussion of \^hicli car- 

 ries the science through its subsequent revolutions, are raised by it ; 

 and we may find that its perpetual function, of which it can never be 

 discharged, is to recall attention from temporary physical solutions to 

 the insoluble problems themselves. 



The kinetical factor is constituted by the whole series of the physi- 

 cal sciences, though at any particular epoch it takes the character of 

 the dominant science. Each stage in the development of Psychology 

 corresponds to some stage in the evolution of the natural sciences ; by 

 each such transition has each psychological development been caused 

 and conditioned ; and the progress of Psychology in fundamental 

 truth, and its more complete emancipation from Theology and Meta- 

 physics, are to be measured by the degree in wliicli physical methods, 

 pliysical conceptions, and even physical metapliors, have been aj^plied 

 to the interpretation of the facts of mind. 



The primitive savage, looking out upon the w^orld, finds no God ; 

 gazing inward upon himself, perceives no Soul ; and thinking of the 



