310 PHILOSOPHY OF ZOOLOGY. 
pressing the wants or the enjoyments of the active powers. 
In addition to this natural language, man has contrived ar- 
tificial sounds, and artificial signs, to express all his percep- 
tions, reflections, and feelings, to others of his race, absent 
as well as present,—attributes which give him a decided 
superiority over the brutes. It is by means of these, that 
the improvements or the experience of one generation are 
transmitted to another; so that, while the brutes must ac- 
quire all their knowledge by experience, man derives his 
most valuable acquisitions from tradition. 
We have likewise seen, that the power of restraining the 
impulses of the active powers is weak in the lower ani- 
mals; but, in man, it is capable of exerting itself in a great- 
er degree, thus giving him a more complete command over 
himself, and consequently over the objects around him. 
These various instances of superiority, unfold to us the 
steps by which man is destined to rise in the scale of civi- 
lized life, and acquire that dominion over nature which he 
upholds by his wisdom. Man, therefore, is far exalted 
above the brutes, by a superior degree of perfection in his 
intellectual faculties ; by a greater power of restraint over 
his instincts ; and by readier methods of communicating his 
ideas and feelings,—rather than by a difference in the na- 
ture of his mental constitution, 
The importance of the nervous system to the existence 
and wellbeing of animals, naturally excited inquiries con- 
cerning its structure and modifications in the different 
races of animals, and led to the adoption of the charac- 
ters which these furnished in their classification. We have 
already presented a view of the animal kingdom, at the 
conclusion of our remarks on the structure of the nervous 
system, in which the classes are arranged according to dif- 
ferences in the organization of this system. 
When we consider the difficulty attending the examina- 
tion of the functions of the nervous system, our ignorance 
