Mr. Mayo on Human Fhysiology. 9.'^ 



for instance, that plants feel, although we have every rea- 

 son to believe the contrary to be the fact. In this and in 

 similar cases, however, we have no means of ascertaining 

 the existence of sensibility. Movements in other beings, 

 such as in ourselves are voluntary, constitute our only evi- 

 dence that they feel. 



" Volition is another simple affection of consciousness, to 

 define the nature of which we have but to abstract from it 

 the phenomena usually presented to the mind in combination 

 with it. We that are blessed with health habitually con- 

 nect volition with a sense of muscular effort ; but when the 

 limbs are paralysed, the patient looks at them and wills in 

 vain their movement; with him the act of volition, like the 

 apprehension of an humorous conceit, or any other purely 

 intellectual operation, is unattended with sensation. Vo- 

 lition, in the sense to which it is commonly limited by 

 physiologists, means but the attempt to produce muscular 

 action ; and the affection of the mind, though, during health, 

 habitually followed by this result, may take place perfectly, 

 as happens on various occasions, including the instance 

 above selected, without a single muscular fibre moving. 



'' Besides sensation and volition, a third element is wanted 

 to compose a scheme of consciousness analogous to our own. 

 Some cause must be supposed capable of determining the 

 occasions upon which the will energizes : motives must 

 exist to actuate the will. 



** Upon referring to the ordinary operations of our own 

 minds, volition appears to take place, whenever we have 

 reason to anticipate a certain degree of gratification or 

 advantage from its exertion. We know, by experience, the 

 prompt influence of the will upon our muscular frame : — 

 we are able to conjecture, with more or less certainty, the 

 consequences of different voluntary actions ; and we will, 

 with a general or precise understanding of what the result 

 will be, and in order to obtain it. A hungry person 

 knows that the food he prepares to eat will gratify his 

 appetite ; a drowning person hopes that his cries will bring 

 people to his assistance. But there are other instances in 

 which conscious motives can be assigned for voluntary ac- 

 tions. The infant at the breast, or struggling when first 

 plunged into water, employs efforts for its sustenance or 

 preservation no less voluntary than those already instanced. 

 But in the infant, the motive which leads to the voluntary 

 effort is not a calculation of advantage, but a spontaneous 

 tendency, a blind inclination, an instinct. 



