6 DEVELOPMENT AND PURPOSE CHAP. 



consciousness. To many of them the presence of con- 

 sciousness appears generally essential. Nor are they 

 uniform and undeviating in their course. On the contrary 

 they are varied from occasion to occasion and even from 

 moment to moment, and varied, it would seem, in accord- 

 ance with an intelligent appreciation of the needs of the 

 situation. None the less, such examples as those quoted, 

 and the extreme difficulty of definitely formulating any 

 alternative view have suggested an interpretation which 

 would reduce all conscious and therewith all psychical 

 activity to the level of a vastly complicated and glorified 

 mechanism. The series of mechanical changes it is con- 

 ceived must be unbroken. As the speck of dust sets up 

 a train of molecular movements which ultimately issues in 

 the secretion of a tear, so the stimulus of printed words 

 affecting the optic nerve spreads its wave of influence over 

 the brain and, no doubt through combinations of infinite 

 complexity with other influences, produces by a strictly 

 physical process some final modification in the reader's 

 conduct of life. All that the man so affected is aware of 

 is a series of changes in his own mind new thoughts, 

 emotional suggestions, the interaction of new and old 

 experiences, the crystallisation ultimately of half-formed 

 suggestions into a new and definite rule of conduct. To 

 him the suggestions appear as the antecedent conditions 

 and his own resolutions as the complete and sufficient cause 

 of the line of conduct that he adopts. But if he propounds 

 this theory to a convinced exponent of mechanical uni- 

 formity he is met by some exceedingly difficult questions. 

 The process in question begins with something physical, 

 that is to say with masses in motion, and it ends with some- 

 thing physical ; a physical basis, the brain and nervous 

 system, is a necessary condition of its continuance and 

 successful termination. Are we then to understand that 

 there is at some point a break in the physical process ? If 

 so, we shall have to say where precisely the break occurs, 

 and this without making arbitrary assumptions we shall 

 have great difficulty in doing. Not only so, but what is 

 more serious, we shall have to assume that at the point 

 where the break occurs a uniform mechanical process by 



