Cambridge Philosophical Society, 231 



duced by the physical constitution of the agent independent of the 

 understanding ; the other rational, induced by the discernment of 

 some object of desire in the end to be accomplished, and of course 

 implying a previous conception of the action in question. 



Familiar instances of instinctive action are then pointed out, from 

 whence it would appear that the sensations of touch felt on contact 

 of any part of the living frame with a foreign body operate as motives 

 to instinctive exertion through the instrumentality of that part of 

 the muscular frame on which the sensible impression is made, in- 

 stinctively impelling the sentient being to muscular reaction against 

 the material cause of the sensation, or leading him to shrink from 

 it if the sensation is of a painful nature. 



Attention is directed in particular to the action of an infant in- 

 stinctively closing his hand upon a finger placed within his palm ; 

 and it is argued that the effect of such an action on his understanding 

 will be the direct apprehension of body, a complex object consisting 

 of surface (undeveloped as yet in form and magnitude) apprehensible 

 by tactual sensation ; and substance, revealed by resistance to mus- 

 cular exertion, constituting a new kind of being essentially different 

 from any of those discerned by means of the five senses. 



The relation between body and space is illustrated by comparison 

 with the case of light and darkness, the second of the two correla- 

 tives belonging in each case to Locke's class of positive ideas from 

 negative causes. As he who has once apprehended light is subse- 

 quently enabled to look for that phenomenon in a direction from 

 whence no rays actually penetrate the eye, so, it is argued, will he 

 who has once made use of his hand in the apprehension of body be 

 enabled to stretch out the same member in feeling for body when 

 none is actually within reach ; and as in the former case the failure 

 of the effort to discover light results in the sensible impression of 

 black or darkness, so in the latter case the effort unsuccessfully 

 aimed at the apprehension of body will take effect on the intelli- 

 gence in the direct cognition or actual experience of space, viz. of 

 that particular portion of space through which the hand is moved in 

 the unsuccessful search after body. 



Thus the notion of space, like that of body, or of any sensible 

 phenomenon, is traced to the actual experience of the thing itself 

 in concrete existence. The subsequent enlargement of the idea, so 

 as to comprehend the space occupied by the solid substance of bodies 

 and that which stretches away to infinity in all directions around us, 

 is duly accounted for on the same principle ; and that impossibility 

 of conceiving the destruction of any portion of space, on which so 

 much stress has been laid as establishing the necessity of a deeper- 

 seated origin than simple experience, is shown to be the natural 

 consequence of the negative foundation of the idea as explained by 

 the analogy of light and darkness. 



May 13. — Results* connected with the theory of the singular solu- 



* This communication is the abstract of a part of a paper not yet com- 

 pleted, and was forwarded to the Society for the purpose of ascertaining 

 whether any examples could be produced destructive of the perfect gene- 

 rality of the results. 



