144 PSYCHOLOGY. 



tips, etc.) are supplied by nerve-trunks of unusual thick- 

 ness, wliicli must supply to every unit of surface-area an 

 unusually large number of terminal fibres. But the varia- 

 tions of felt extension obey probably only a very rough law 

 of numerical proportion to the number of fibres. A sound 

 is not twice as voluminous to two ears as to one ; and the 

 above-cited variations of feeling, when the same surface i& 

 excited under different conditions, show that the feeling ia 

 a resultant of several factors of which the anatomical one 

 is only the principal Many ingenious hypotheses have 

 been brought forward to assign the co-oj)erating factors 

 where different conditions give conflicting amounts of felt 

 space. Later we shall analyze some of these cases in de- 

 tail, but it must be confessed here in advance that many of 

 them resist analysis altogether. * 



* It is worth while at this point to call attention with some emphasis to 

 the fact that, though the anatomical condition of the feeling resembles the 

 feeling itself, such resemblance cannot be taken by our understanding to 

 explain why the feeling should be just what it is. We hear it untiringly- 

 reiterated by materialists and spiritualists alike that we can see no possible 

 inward reason why a certain brain-process should produce the feeling of 

 redness and another of anger : the one process is no more red than the 

 other is angry, and the coupling of process and feeling is, as far as our 

 understanding goes, a juxtaposition pure and simple. But in the matter of 

 spatial feeling, where the retinal patch that produces a triangle in the mind 

 is itself a triangle, etc., it looks at first sight as if the sensation might be a 

 direct cognition of its own neural condition. Were this true, however, our 

 sensation should be one of mnltitude rather than of continuous extent ; for 

 the condition is number of optical nerve-termini, and even this is only a 

 remote condition and not an immediate condition. The immediate condi- 

 tion of the feeling is not the process in the retina, but the process in the 

 brain ; and the process in the brain may, for aught we know, be as unlike 

 a triangle, — nay, it probably is so, — as it is imlike redness or rage. It is 

 simply a coincidence W^^X in the case of space one of the organic conditions, 

 viz., the triangle impressed on the skin or the retina, should lead to a rep- 

 resentation in the mind of the subject observed similar to that which it 

 produces in the psychological observer. In no other kind of case is the 

 coincidence found. Even should we admit that we cognize triangles in 

 space because of our immediate cognition of the triangular shape of our 

 excited group of nerve-tips, the matter would hardly be more transparent, 

 for the mystery would still remain, why are we so much better cognizant 

 of triangles on our finger-tips than on the nerve-tips of our back, on our 

 eye than on our ear, and on any of these parts than in our brain ? Thos. 

 Brown very rightly rejects the notion of explaining the shape of the space 

 perceived by the shape of the 'nervous expansion affected.' "If thia 



