ASSOCIATION. 583: 



similaiitj. Wln^, in these latter brains, action should tend 

 to focalize itself in small spots, while in the others it fills 

 patiently its broad bed, it seems impossible to guess. 

 Whatever the difference may be, it is what separates the 

 man of genius from the prosaic creature of habit and rou- 

 tine thinking. In Chapter XXII we shall need to recur 

 again to this point. 



ASSOCIATION IN VOLUNTARY THOUGHT. 



Hitherto we have assumed the process of suggestion of 

 one object by another to be spontaneous. The train of 

 imagery wanders at its own sweet will, now trudging in sober 

 grooves of habit, now with a hop, skip, and jump darting^ 

 across the whole field of time and space. This is revery, 

 or musing ; but great segments of the flux of our ideas 

 consist of something very different from this. They are 

 guided by a distinct purpose or conscious interest. As 

 the Germans say, we nachdenken, or think towards a certain 

 end. It is now necessary to examine what modification is 

 made in the trains of our imagery by the having of an end 

 in view. The course of our ideas is then called voluntary. 



Physiologically considered, we must suppose that a 

 purpose means the persistent activity of certain rather 

 definite brain-processes throughout the whole course of 

 thought. Our most usual cogitations are not pure reveries, 

 absolute driftings, but revolve about some central interest 

 or topic to which most of the images are relevant, and to- 

 wards which we return promptly after occasional digres- 

 sions. This interest is subserved by the persistently active 

 brain-tracts we have supposed. In the mixed associations 

 which we have hitherto studied, the parts of each object 

 which form the pivots on which our thoughts successively 

 turn have their interest largely determined by their con- 

 nection with some general interest which for the time has 

 seized upon the mind. If we call Z the brain-tract of gen- 

 eral interest, then, if the object abc turns up, and b has 

 more associations with Z than have either « or c, h will be- 

 come the object's interesting, pivotal portion, and will call up 

 its own associates exclusively. For the energy of &'s brain- 

 tract will be augmented by Z's activity, — an activity which. 



