and functions of the nemes. 403 
in man ; that it is a pneumatic as much as a manducatory 
organ ; that it is the organ of the voice and of speech, as of 
taste and exquisite feeling. It would indeed be matter of sur- 
prise, if the same nerve served for the action of gnawing and 
feeding in the lower animals of simple structure, and also for 
the governance of those complicated operations, which serve 
to interpret the wants and sentiments of man. 
Such are the views which naturally arise from an acquaint- 
ance with the nerves of the human body ; but a comparison 
of them, with those of the lower classes of animals, enables us 
to establish a more lucid order, and that not in an arbitrary 
manner, but perfectly according to nature. 
The nerves of all creatures may be divided into two parts, or 
systems ; the one simple and uniform , the other irregular and 
complex, in proportion to the complexity of organization. 
When the nerves of the face, mouth, throat, and neck of 
the human subject are minutely displayed, it seems impracti- 
cable to reduce the numerous nerves which cross and entwine 
with each other to two distinct classes ; yet nothing is more 
certain than that this may be done, and by an easy and natural 
method. 
The principle which is to guide us, is obtained by ascertain- 
ing what parts of the organization of an animal are necessary 
to life and motion ; what organs are superadded as the animal 
advances in the scale of existence, as necessary to higher and 
more complex enjoyments and actions. 
Where an animal is endowed with mere sensation and loco- 
motion, where there is no central organ of circulation, and no 
organ of respiration but what is generally diffused over the 
mdcccxxi. 3 F 
