160 Mk WEDGWOOD, ON THE KNOWLEDGE 



our hand over a particular body, it must at least be admitted that our conception of the shape 

 and dimensions of the body in question is practically dependant on the tactual sensation and 

 muscular exertion of which we are conscious in the experiment, just as the particular colour or 

 taste apprehended in the act of sight or of eating is dependant upon the physiological affections 

 simultaneously taking place in the eye or the palate. It will then in the first place be 

 incumbent on the supporter of the necessary theory to explain in what essential particular 

 a revelation by necessary judgment so depending upon simultaneous modifications of the 

 organic system differs from the ordinary experience of sense ; but whether he succeed in 

 establishing such a distinction or no ; whether the muscular and sentient action practically 

 efficient in the apprehension of a given body be considered as the occasion merely on which 

 certain conceptions of form and magnitude are supplied from the inherent constitution of 

 the understanding itself, or whether they be considered as elements of a complex operation in 

 which the form and magnitude as well as the substance of the body under examination are 

 made the object of direct experience ; the investigation of the conditions of tactual sensation 

 and muscular action in dependence on which the elementary notions of form and magnitude 

 are originally revealed to the understanding, will remain a problem of equal interest. 



The stumbling-block which has so long stood in the way of a successful theory of the 

 notion of extension is the assumption that the intelligence can only derive information from the 

 exercise of muscular power through a conception of the outward manifestation in the bodily 

 member employed as special organ of the exertion. It is taken for granted that nothing can 

 be learned from the action of the finger but what can be gathered from the knowledge of the 

 motion effected in that member of our body, or prevented from taking place by some external 

 obstacle. 



In this assumption there is an entire oversight of the cardinal fact of instinctive action. 

 The rational exercise of a power, or exertion to which the agent is led from regarding it as a 

 means of obtaining some real or supposed gratification, obviously supposes a previous acquaint- 

 ance with the power to be exerted, and as the knowledge of each elementary faculty can only 

 be acquired by actual experience of the function it fulfils, it is plain that the rational (or 

 as Cousin calls it the voluntary) exercise of each of our faculties must be preceded by what 

 he terms the spontaneous exercise of the same power ; that is to say, by action spontaneous as 

 it were in the organic system unguided by the intention of the thinking faculty. 



The knowledge of muscular action, or capacity of thinking on, and consequently of intend- 

 ing a definite exertion of muscular power can only be acquired by previous experience of that 

 kind of action. It is plain therefore that there must be some provision in our sentient frame 

 by means of which we may be excited to muscular action in total ignorance, as well of the 

 power to be exerted, as of every object of thought the knowledge of which essentially depends 

 upon the exercise of the same power — in ignorance accordingly of the existence of body of any 

 kind, and especially of the bodily member employed as organ of the exertion. Such a provision 

 may be found in the principle of Instinctive Action, the more complicated instances of which 

 are so striking to the imagination where an animal is seen laboriously compassing a purpose of 

 which lie can have no previous conception. The extent to which we are indebted to the same 

 principle in executing the ordinary functions of active life may easily escape observation. 



