Individual through the Nervous System. 99 



vinced of this truth, one must examine the numerous and divers 

 impressions produced by a single object, when in contact with 

 an organ of sense, and take into account the confusion which 

 would result if man did not possess a power of unification by 

 which he co-ordinates and transforms his impression into a 

 distinct idea. For example, if a man be the object brought into 

 contact with the organ of vision, a distinct conception would be 

 wanting ; the impressions of position, form, colour, size, move- 

 ment, and distance would be purposeless, because, striking the 

 eye simultaneously, they are in like manner transmitted by the 

 optic nerves to the visual centre in the cerebrum. Here these 

 simultaneous impressions necessarily determine multiple modi- 

 fications in the brain, which modifications can produce sensation 

 by being reduced to a unity whose substantive man is the re- 

 presentative. When tactile and auditory impressions are added, 

 there arises an increase of modifications, the combined result of 

 which bears no resemblance to the distinct and unique sensa- 

 tion. The effect is not unlike the confused impressions which 

 occur in dreams, and it is only when all these varied and 

 manifold impressions are brought under a general name that we 

 obtain a clear and positive sensation, an accurate mental picture, 

 and can conceptively say — Behold a man ! This reasoning re- 

 minds us of the intelligent blind man to whom a careful and 

 accurate definition of "■ scarlet " was given, and who, in reply to 

 the inquiry as to whether he understood it, said, " Oh, yes, it is 

 like the sound of a trumpet." He summed up in a single con- 

 ception the sensations of which he was capable. iMoreover, 

 these considerations lead us to the conclusion that such concep- 

 tion largely depend upon previous instruction. We do not 

 instinctively possess such ideas as those of stranger, friend, 

 painting, book, or number, but the necessary accompaniment 

 of earlier mental development is incontestable in the conception 

 of such ideas. It is important to recognise that our activity 

 reacts on the plurality of the cerebral modifications, which 

 result from the plurality of these impressions ; that it invests 

 them by means of language with the character of unity ; and 



