168 COSMLG PHILOSOPHY, [pt. u 



Purely intellectual acts also become to a certain extent 

 autonuitic with practice, as was indeed implied in some of 

 the foregoing illustrations. Not only the combination of 

 words into a sentence, but the combination of sentences into 

 a proposition, and the combination of propositions into a 

 theory, is effected more and more rapidly, until the pro- 

 cess hardly attracts attention. In a complicated exposition 

 like the present, numerous seientific theorems, at first 

 laboriously comprehended one by one, are wrapped up to- 

 gether and thrown into some subordinate clause of a sen- 

 tence, the total being so obvious as not to withdraw the 

 attention from the main current of thought while writing. 

 In such facts we have a partial explanation of many of 

 the phenomena of what is called unconscious or " sub-con- 

 .scious " thiiiking. And thus, too, are to be explained those 

 sudden flashes of insight, scientific or poetical, which in 

 early times were attributed to inspiration or dictation from 

 without. Obviously without a good deal of such automatic 

 acting and thinking, we could achieve but little in art or 

 science. We should never become good pianists if we had 

 to keep paying attention to all the requisite muscuhir ad- 

 justments ; and science would advance but slowly if at 

 each step of an intricate inquiry in dynamics it were neces- 

 sary to stop and reflect upon the elementary laws of matter 

 and motion. 



The physical interpretation of these secondary automatic 

 processes is not difficult, accordiiig to the hypothesis here 

 expounded. During the process of learning, there is an 

 extensive formation of new transit-lines, and consequently 

 an appreciable interval between the accumulation of mole- 

 cular disturbance in the cerebral cells and its discharge. 

 Impressions persist long enough to be compared together, 

 and accordingly there is reason and there is volition. There 

 is a maximum of consciousness, because there is a maximum 

 duration of the nutritive changes, and hence weariness soon 



