246 THE DIRECTION OF MOTION. 



ther details it will be manifest that a like interpretation 

 may be given to the succession of all other nervous changes. 

 If in the surrounding world there are objects, attributes, or 

 actions, that usually occur together, the effects severally 

 produced by them in the organism will become so connected 

 by those repetitions which we call experience, that they also 

 will occur together. In proportion to the frequency with 

 which any external connexion of phenomena is experienced, 

 will be the strength of the answering internal connexion of 

 nervous states. Thus there will arise all degrees of cohesion 

 among nervous states, as there are all degrees of common- 

 ness among the surrounding co-existences and sequences 

 that generate them: whence must result a general corre- 

 spondence between associated ideas and associated actions in 

 the environment.* 



The relation between emotions and actions may be simi- 

 larly construed. As a first illustration let us observe what 

 happens with emotions that are undirected by volitions. 

 These, like feelings in general, expend themselves in gen- 

 erating organic changes, and chiefly in muscular contrac- 

 tions. As was pointed out in the last chapter, there result 

 movements of the involuntary and voluntary muscles, that 

 are great in proportion as the emotions are strong. It re- 

 mains here to be pointed out, however, that the order in 

 which these muscles are affected is explicable only on the 

 principle above set forth. Thus, a pleasurable or painful 

 state of mind of but slight intensity, does little more than 

 increase the pulsations of the heart. Why? For the rea- 

 son that the relation between nervous excitement and vas- 

 cular contraction, being common to every genus and species 

 of feeling, is the one of most frequent repetition ; that hence 

 the nervous connexion is, in the way above shown, the one 



* This paragraph is a re-statement, somewhat amplified, of an idea set 

 forth in the Medico- Chirurgical Review for January, 1859 (pp. 189 and 190); 

 and contains the germ of the intended fifth part of the Principles of Psy- 

 chology, which was withheld for the reasons given in the preface to that work. 



