122 



CHAP. VII. 



Of Animal Economy, 



HE nerves, which extend themselves into all 

 parts from the brain, are distinguished into several prin- 

 cipal divisions, that are more or less numerous, or more 

 or less extended. Each division reaches to the part for 

 which it is destined, and whose structure corresponds 

 with the functions appointed for it to exercise. 



Feeling, sight, hearing, taste, and smell, are five 

 kinds of senses, which contain under them an almost in- 

 finite number of species. The shaking which the me- 

 diate or immediate impression of objects produces on 

 the nerves, give birth to those different kinds of sensa- 

 tions, which may all be reduced to feeling, of which 

 they are properly only modifications. The organs of 

 the senses are the instruments of these modifications. 

 The number, extent, and delicacy of the senses, consti- 

 tute the degree of animal perfection. 



The nerves, which seem to resemble the strings of a 

 musical instrument, are not stretched like them. Some 

 animals are endued with an exquisite sensation, that are 

 themselves little otherwise than a thick jelly ? How then 

 can we admit of elastic strings in this jelly ] While the 

 fetus is altogether gelatinous, it regulates at that time 

 its members. With what amazing swiftness then must 

 the impressions of objects communicate themselves to 

 the soul ! and with what wonderful celerity must the 

 members obey the will ! Thus we are led to suppose in 

 the nerves a very subtle and elastic fluid, whose mo- 

 tions, being analogous to those of light or electrical 



