CHAPTER XXVII. 



CEREBRAL MENTAL SUBSTRATA. 



AFTER the first ' Sensation ' nothing strictly answering to 

 this term exists. We only consciously realize any impres- 

 sion, as of such and such a nature, by automatic com- 

 parison of it with other impressions which have gono 

 before it. A simple ' Sensation ' can, in fact, scarcely 

 exist in consciousness, nor can it be imagined by us in 

 our present phase of mental evolution. Our so-called 

 ' Sensations ' are really Perceptions. In one and the same 

 act or state each of them embodies Feeling and Intelli- 

 gence in indissoluble connection. 



A seat of ' simple ' or ' brute ' Sensation is, therefore, 

 not to be looked for. The seats of conscious sensibility in 

 the only intelligible phase in which such states can exist 

 for us are centres for Perception*. 



As the act of Perception involves the automatic com- 

 parison of present impressions with revived past impres- 

 sions of the same kind, as well as of some or all other 

 kinds of impressions capable of being yielded by the 

 Object perceived, it happens that even in the simplest so- 

 called ' Sensation ' the conjoint activity is necessitated of 

 no one limited tract of convolutional grey matter but 

 rather of widely extended cell-and-fibre mechanisms 

 corresponding, it may be, with many more or less diffused 

 and complexly related Perceptive Centres (p. 522). 



Seeing that each Perceptive Centre forms the basis or 

 starting point of different processes of Ideation, and, 

 * See pp. 176, 524, and " Nature," Jan. 20, 1870, p. 309. 



