72 
THE DESCENT OF MAN. 
. Part 5. 
its intellectual powers had become as well developed, or 
nearly as well developed, as in man. For, firstly , the 
social instincts lead an animal to take pleasure in 
the society of its fellows, to feel a certain amount of 
sympathy with them, and to perform various services 
for them. The services may be of a definite and evi- 
dently instinctive nature ; or there may be only a wish 
and readiness, as with most of the higher social animals,, 
to aid their fellows in certain general ways. But these 
feelings and services are by no means extended to all 
the individuals of the same species, only to those of 
the same association. Secondly , as soon as the mental 
faculties had become highly developed, images of all 
past actions and motives would be incessantly passing 
through the brain of each individual ; and that feeling 
of dissatisfaction which invariably results, as we shall 
hereafter see, from any unsatisfied instinct, would arise, 
as often as it was perceived that the enduring and 
always present social instinct had yielded to some other 
instinct, at the time stronger, but neither enduring in 
its nature, nor leaving behind it a very vivid impres- 
sion. It is clear that many instinctive desires, such as 
that of hunger, are in their nature of short duration 
and after being satisfied are not readily or vividly re- 
called. Thirdly , after the power of language had been 
acquired and the wishes of the members of the same 
community could be distinctly expressed, the common 
opinion how each member ought to act for the public 
good, would naturally become to a large extent the guide 
to action. But the social instincts would still give the 
impulse to act for the good of the community, this im- 
pulse being strengthened, directed, and sometimes even 
deflected by public opinion, the power of which rests, as 
we shall presently see, on instinctive sympathy. Lastly 
habit in the individual would ultimately play a very 
