THE LAWS OF HABIT. 443 



charged is an express order from the ideational centers after this de- 

 liberation has been gone through. 



In habitual action, on the contrary, the only impulse which the 

 centers of idea or perception need send down, is the initial impulse, the 

 command to start. This is represented in the diagram by V ; it may be 

 a thought of the first movement or of the last result, or a mere per- 

 ception of some of the habitual conditions of the chain, the presence, 

 e. g., of the key-board near the hand. In the present case, no sooner 

 has the conscious thought or volition instigated movement A, than A, 

 through the sensation a, of its own occurrence awakens B reflexly ; B 

 then excites C through b, and so on till the chain is ended, when the 

 intellect generally takes cognizance of the final result. The process, 

 in fact, resembles the passage of a wave of "peristaltic" motion down 

 the bowels. The intellectual perception at the end is indicated in the 

 diagram by the effect of G being represented, at G', in the ideational 

 centers above the merely sensational line. The sensational impres- 

 sions, a, b, c, d, e, f, are all supposed to have their seat below the idea- 

 tional lines. That our ideational centers, if involved at all by a, b, c, 

 d, e, f, are involved in a minimal degree, is shown by the fact that the 

 attention may be wholly absorbed elsewhere. "We may say our pray- 

 ers, or repeat the alphabet, with our attention far away. 



"A musical perforrner will play a piece which has become familiar 

 by repetition, while carrying on an animated conversation, or while 

 continuously engrossed by some train of deeply interesting thought ; 

 the accustomed sequence of movements being directly prompted by 

 the sight of the notes, or by the remembered succession of the sounds 

 (if the piece is played from memory), aided in both cases by the guid- 

 ing sensations derived from the muscles themselves. But, further, a 

 higher degree of the same ' training ' (acting on an organism specially 

 fitted to profit by it) enables an accomplished pianist to play a difficult 

 piece of music at sight ; the movements of the hands and fingers fol- 

 lowing so immediately upon the sight of the notes, that it seems 

 impossible to believe that any but the very shortest and most direct 

 track can be the channel of the nervous communication through which 

 they are called forth. The following curious example of the same 

 class of acquired aptitudes, which differ from instincts only in being 

 prompted to action by the will, is furnished by Robert Houdin : 



" With a view of cultivating the rapidity of visual and tactile per- 

 ception, and the precision of respondent movements, which are neces- 

 sary for success in every kind of prestidigitation, Houdin early prac- 

 ticed the art of juggling with balls in the air ; and having, after a 

 month's practice, become thorough master of the art of keeping up 

 four balls at once, he placed a book before him, and, while the balls 

 were in the air, accustomed himself to read without hesitation. ' This,' 

 he says, 'will probably seem to my readers very extraordinary ; but I 

 shall surprise them still more when I say that I have just amused my- 



