100 The Influence of Language and Environment upon the 



that this unity, which is neither more nor less than an idea, is 

 a true conception. Now, this conception is not definitively an 

 act of the spirit, as described by some philosophers under the 

 name of perception, as distinct from sensation, as if to feel and 

 to perceive were operations entirely independent of each other; 

 and this is confirmed by experience. When the operator gives 

 sight to a blind person, or hearing to the deaf, the resulting 

 sensorial impressions would be confused and barren were it not 

 for the embodied experience of a previous education. Though, 

 perhaps, infinitesimally distinct in point of time only, sensation 

 and perception are, therefore, one and the same phenomenon 

 of human activity, originating in groups of sensorial impressions, 

 and transforming them by the aid of a sign into an idea, or into 

 a positive conception. We insist upon this point of doctrine, 

 because it furnishes us with valuable information as to the 

 number and extent of the cerebral operations — operations 

 determined in man by the signs of language. 



But this is not all. Sensation has not always the same extent 

 or degree of intensity. When impressions reach us unexpec- 

 tedly, they produce sensations less perfect than when they are 

 anticipated. We are not contented in the last case with distin- 

 guishing and naming a group of impressions ; we go further, 

 we detach one or more impressions from the whole, and name 

 them successively — in other words, having formed a clear 

 conception of an object, we then discern its parts and its 

 attributes. In this way a botanist, in examining flowers that 

 the horticulturist has often contemplated, sees organs, colours, 

 and conformations to which the other is a perfect stranger. 

 Similarly, a well-informed physician, in ausculating the chest 

 of a patient, hears and understands sounds which few could 

 either hear or comprehend. The explanation of this is to be 

 found in the fact that there exist in the mind of these men 

 qualities which possibly exist in others, but which, from want 

 of training and cultivation, might just as well not be there. 

 These qualities — concentration of mind and unremitting atten- 

 tion to the minutest details — have been developed by the aid of 



