PHYSIOLOGICAL" PSYCHOLOGY 483 



The point of departure, then, lies in the philosophical line. Little 

 as he could foresee the future influence of his theory, Locke raised, in a 

 manner, the entire question of the relation between consciousness and 

 the physiological organism by his famous distinction between the 

 primary and secondary qualities of body. 3 Qualities like color, odor, 

 hardness and sound, he called secondary, because they can not become 

 effective components of consciousness unless the appropriate organs 

 cooperate. Neither color nor sound resides in nature, but motions of 

 such and such amplitude. For us, therefore, color and sound happen 

 to be interpretations by eye and ear of something incommensurable with 

 the perceptions in consciousness. On the contrary, qualities such as 

 resistance and extension belong to objects in their own right, and 

 persist independent of any cooperation by our sense organs. Locke 

 did not grasp the philosophical problems, involved here, much less the 

 extreme complexity of the physiological processes he assumed. How- 

 ever, he does advert to one of the difficulties embedded in his view — the 

 " mystery," as it remains even yet, of space perception : 



I shall here insert a problem of that very ingenious and studious promoter 

 of real knowledge, the learned and worthy Mr. Molineux, which he was pleased 

 to send me in a letter some months since; and it is this: — "Suppose a man 

 born blind, and now adult, and taught by his touch to distinguish between a 

 cube and a sphere of the same metal, and nighly of the same bigness, so as to- 

 tell, when he felt one and the other, which is the cube, which the sphere. Sup- 

 pose then the cube and the sphere placed on a table, and the blind man be made 

 to see-.quaere, whether by his sight, before he touched them, he could now dis- 

 tinguish and tell which is the globe, which the cube?" To which the acute 

 and judicious proposer ansAvers, " Not. For, though he has obtained the experi- 

 ence of how a globe, how a cube affects his touch, yet he has not yet obtained the 

 experience that what affects his touch so or so, must affect his sight so or so; 

 or that a protuberant angle in the cube, that pressed his hand unequally, shall 

 appear to his eye as it does in the cube." — I agree with this thinking gentleman, 

 whom I am proud to call my friend, in his answer to this problem; and am of 

 opinion that the blind man, at first sight, would not be able with certainty to 

 say which was the globe, which the cube, whilst he only saw them; though he 

 could unerringly name them by his touch, and certainly distinguish them by 

 the difference of their figures felt. This I have set down, and leave with my 

 reader, as an occasion for him to consider how much he may be beholden to 

 experience, improvement and acquired notions, where he thinks he had not the 

 least use of, or help from them. 4 



As the last sentence indicates, this reference remains incidental 

 rather than determining for Locke. 



It was left for his successor and critic Berkeley to give special form 

 to the problem for its own sake, in his " Essay towards a New Theory 

 of Vision''' (1709). With remarkable prescience, he writes: 



Rightly to conceive the business in hand, we must carefully distinguish 



3 " Essay concerning Human Understanding," Bk. II.; Chap. VIII. 



1 " Essay concerning Human Understanding," Bk. II., Chap. IX., Sect. S. 



