NATURAL HISTORY. 105 



were present, he yet did not seem to have mane such 

 reflections even upon these, as might reasonably have 

 been expected. The young man was not, however, 

 deficient in understanding ; but the understanding of 

 a man, deprived of all commerce with others, is so very 

 confined, that the mind may be said to be under the 

 control of its immediate sen sations. 



" It is highly possible, nevertheless, to communicate 

 ideas to deaf men, which they previously wanted, and 

 even to give them very precise notions of abstract and 

 general subjects, by means of signs and of Jetters. A 

 person born deaf may, by time and application, be 

 taught to read, to write, and even by the motions of 

 the lips to understand what is said to him. This is a 

 plain proof how much the senses resemble, and may 

 supply the defects of each other. It is probable, how- 

 ever, that as most of the motions of speech are made 

 within the mouth by the tongue, the knowledge from 

 the motion of the lips can be but very confined. 



The sense of feeling is spread over the whole bo'dy, 

 but it employs itself differently in different parts. 

 The sensation which results from feeling, cannot be 

 excited otherwise than by the' contact and immediate 

 application of the superfices of some foreign body to 

 that of our own. If we apply a foreign body against 

 the. breast, or upon the shoulder of a man, he will feel 

 it ; that is, he will know that there is a foreign body 

 which touches him. But he will not have a single 

 idea of the form of this body, because the breast touch- 

 ing the body in a single plain, or surface, he cannot 

 gather from it any knowledge of this body. It is the 

 same with respect to all other parts of the body, which 

 cannot adjust themselves upon the surface of foreign 

 bodies, and bend themselves, to embrace at one time- 



'Vol. I. N 



