44 PHYSICAL EXPKESSION. 



of consciousness, but we are to study their ex- 

 pression or objective concomitants. All that can 

 be observed are the ejecta, or outward visible signs ; 

 the coexistence of the subjective condition is an 

 inference dependent upon the uniform experience 

 that such and such outward or objective sign is 

 always, or almost uniformly, accompanied by a 

 certain subjective condition or feeling. In the ex- 

 pression of physical pain the angles of the mouth 

 are depressed. This statement is justified by the 

 frequent, almost uniform, observation that, when 

 the angles of the mouth are markedly depressed, 

 inquiry shows that there is some source of physical 

 pain in the man or animal ; and conversely, that, in 

 many cases where there is known to be pain, 

 examination has shown that the angles of the 

 mouth are drawn down. It has been said by some 

 that pain must be the cause of the depression of 

 the angles of the mouth. We do not know what 

 pain is; it is a subjective condition. We do know 

 that the depression of the angles of the mouth is 

 due to muscular contraction, and that the muscular 

 contraction is due to a nerve-current from the nerve- 

 centre. It is, then, the condition of the nerve-centre 

 corresponding to the muscles which depress the 

 angles of the mouth, that is so uniformly affected 

 when there is a source of pain in the subject; in 

 fact, all the special irritations which cause pain, 

 seem to affect the nerve-centres of the depressor 

 muscles of the angles of the mouth. This is the 

 knowable objective fact. 



It seems to me that the ground is cleared for us 



