SEC. 4. THE MUSCULAR SENSE. 



When we come into contact with external bodies we are 

 conscious not only of the pressure exerted by the object on our 

 skin, but also of the pressure which we exert on the object. If we 

 place the hand and arm flat on a table, we can estimate the 

 pressure exerted by bodies resting on the palm of the hand, and 

 so come to a conclusion as to their weights ; in this case we are 

 conscious only of the pressure exerted by the body on our skin. If 

 however we hold the body in the hand, we not only feel the 

 pressure of the body, but we are also aware of the muscular 

 exertion required to support and lift it. We possess a muscular 

 sense ; and we find by experience that when we trust to this 

 muscular sense as well as to sensations of pressure, we can form 

 much more accurate judgments concerning the weight of bodies than 

 when we rely on sensations of pressure alone. When we want to tell 

 how heavy a body is, we are not in the habit of allowing it simply to 

 press on the hand laid flat on a table ; we hold it in our hand and 

 lift it up and down. We appeal to our muscular sense to inform 

 us of the amount of exertion necessary to move it, and by help of 

 that, judge of its weight. And in all the movements of our body 

 we are guided, even to an astonishing degree of accuracy, as is well 

 seen in the discussions concerning vision, by an appreciation, more 

 or less distinctly conscious, of the amount of the contraction to 

 which we are putting our muscles. In some way or other we are 

 made aware of what particular muscles or groups of muscles are 

 being thrown into action, and to what extent that action is being 



