ESSAYS 473 



only one admissible, and to refer to others who declare that there is no science of 

 psychology outside Experimental Psychology. Certainly all these subjects have 

 an important bearing on the study of Psychology, and for my own part I have not 

 neglected their aid ; but the assumption that either of these, or any other partial 

 studies, can cover the whole field of Psychology is so absurd as to be in itself a 

 proof of the need of some more extensive discipline. 



Briefly, it may be said that the expositions of physiological-psychology, as, for 

 instance, that of the great authority in these matters, Wundt, will be found to be 

 a discussion of physiology followed by a discussion of psychology. The nexus 

 between the two is never well established. The physical correlatives of thoughts 

 are not thoughts, nor do they, studied objectively, give us an inkling of the 

 thoughts to which they may be the precedent condition. The disturbance of 

 the retina by an ethereal wave is not a sensation of red, for instance, nor is any 

 part of the whole nervous stimulus nor of the corresponding physical reactions, 

 nor the sum-total of these, a colour-sensation. 



Even if our histology were immeasurably more minute and illuminated than 

 it is now, so that we could trace not only all the nerve-strands in the brain, but 

 form an image of the vibrations of the molecules in the reaction to a stimulus, 

 we still would on that ground alone know nothing of the psychic state corre- 

 sponding. It is almost painful to insist on this argument, yet that it is not super- 

 fluous is plain when one listens to the theories, or consults the works, of certain 

 great physiologists who from the height of their achievements look down on 

 psychology. What is lacking in their own system is precisely such a grasp 

 of psychology as would enable them to interpret the results of their investigations. 

 We will see this later in regard to Broca's Convolution. 



With regard to Experimental Psychology, we have learnt to appreciate the 

 value of the results obtained, but to exclude the play of intellect, which seeks to 

 discover the organic cohesion in all these details, would be as absurd as to obtain 

 a great variety of statistics about falling bodies while refusing to consider the 

 mechanical principles applicable to such cases. I have myself employed experi- 

 mental methods freely, particularly in the studies of Memory, but I look on 

 Experimental Psychology as the handmaiden, and not the mistress, in the house 

 of Thought. 



I will not delay to speak of the importance of studies concerning what is 

 called the " Subconscious," nor indeed of the extravagant claims, suggestive of 

 quackery, of those who seek to popularise " psycho-analysis." Nor will I discuss 

 the form of treatment of Psychology usual in the great text-books — they all have 

 a family likeness— nor the authoritative article on Psychology in the Encyclopaedia 

 Britannica. When I have indicated the true scientific method no argument will 

 be needed to convince the reader how superficial and tentative are all these 

 expositions, and what an enormous mass of the literature of psychology has the 

 value which may be accorded to a discourse in mathematics where the solutions 

 offered are complicated, abstruse, ingenious, and all wide of the mark. 



The conditions of a scientific method in Psychology will have been found if we 

 are able to enunciate the central problem in complete generality ; if we exhibit 

 a solution resting on a foundation at least as basic as that of Newton's principles 

 in mechanics; if in the demonstration we conduct the arguments in cogent 

 succession and with rigour ; and if finally, in possession of our principles, we show 

 the fertility of the system in a series of new and important corollaries. The 

 prospect thus held out is as fresh as the methods of realisation are new ; the two 

 circumstances are mutually dependent. . . . 



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