COMMON SENSATIONS. 315 



lead us to think not of a state of the skin, but of proper- 

 ties of some object outside the skin; we believe we feel a 

 cold heavy hard thing which is not the skin. We have, 

 however, no sensory nerves going into the knife and inform- 

 ing us directly of its condition; what we really feel are the 

 modifications of the body produced by the knife, although 

 we irresistibly think of them as properties of the knife of 

 some object that is no part of the body. Let now the knife 

 cut through the skin; we feel no more knife, but ex- 

 perience pain, which we think of as a condition of our- 

 selves. We do not say the knife is painful, but that the 

 finger is, and yet we have, so far as sensation goes, as much, 

 reason to call the knife painful as cold. Applied one way 

 it produced local changes in the skin arousing a sensation of 

 cold, and in another local changes causing a sensation of pain. 

 Nevertheless in the one case we speak of the cold as being 

 in the knife, and in the other of the pain as being in the 

 finger. 



Sensitive parts, such as the surface of the skin, through 

 which we get, or believe we get, information about outer 

 things, are of far more intellectual value to us than sensi- 

 tive parts, such as the subcutaneous tissue into which the 

 knife may cut, which only give us sensations referred to 

 conditions of our own bodies. The former arc called Organs 

 of Special Sense ; the latter are parts endowed with Common 

 Sensation. 



Common Sensations are quite numerous ; for example, 

 pain, hunger, nausea, thirst, satiety, and fatigue. 



What is meant by "organs of some special sense"? What by 

 parts endowed with common sensation? 

 Name some common sensations. 



