The Wealth of Nations: The Butcher, the Brewer and the Baker

This division of labour, from which so many advantages are derived, is not
originally the effect of any human wisdom, which foresees and intends that
general opulence to which it gives occasion. It is the necessary, though
very slow and gradual, consequence of a certain propensity in human
nature, which has in view no such extensive utility; the propensity to
truck, barter, and exchange one thing for another.

Whether this propensity be one of those original principles in human
nature, of which no further account can be given, or whether, as seems
more probable, it be the necessary consequence of the faculties of reason
and speech, it belongs not to our present subject to inquire. It is common
to all men, and to be found in no other race of animals, which seem to
know neither this nor any other species of contracts. Two greyhounds, in
running down the same hare, have sometimes the appearance of acting in
some sort of concert. Each turns her towards his companion, or endeavours
to intercept her when his companion turns her towards himself. This,
however, is not the effect of any contract, but of the accidental
concurrence of their passions in the same object at that particular time.
Nobody ever saw a dog make a fair and deliberate exchange of one bone for
another with another dog. Nobody ever saw one animal, by its gestures and
natural cries signify to another, this is mine, that yours; I am willing
to give this for that. When an animal wants to obtain something either of
a man, or of another animal, it has no other means of persuasion, but to
gain the favour of those whose service it requires. A puppy fawns upon its
dam, and a spaniel endeavours, by a thousand attractions, to engage the
attention of its master who is at dinner, when it wants to be fed by him.
Man sometimes uses the same arts with his brethren, and when he has no
other means of engaging them to act according to his inclinations,
endeavours by every servile and fawning attention to obtain their good
will. He has not time, however, to do this upon every occasion. In
civilized society he stands at all times in need of the co-operation and
assistance of great multitudes, while his whole life is scarce sufficient
to gain the friendship of a few persons. In almost every other race of
animals, each individual, when it is grown up to maturity, is entirely
independent, and in its natural state has occasion for the assistance of
no other living creature. But man has almost constant occasion for the
help of his brethren, and it is in vain for him to expect it from their
benevolence only. He will be more likely to prevail if he can interest
their self-love in his favour, and shew them that it is for their own
advantage to do for him what he requires of them. Whoever offers to
another a bargain of any kind, proposes to do this. Give me that which I
want, and you shall have this which you want, is the meaning of every such
offer; and it is in this manner that we obtain from one another the far
greater part of those good offices which we stand in need of. It is not
from the benevolence of the butcher, the brewer, or the baker that we
expect our dinner, but from their regard to their own interest. We address
ourselves, not to their humanity, but to their self-love, and never talk
to them of our own necessities, but of their advantages. Nobody but a
beggar chooses to depend chiefly upon the benevolence of his
fellow-citizens. Even a beggar does not depend upon it entirely. The
charity of well-disposed people, indeed, supplies him with the whole fund
of his subsistence. But though this principle ultimately provides him with
all the necessaries of life which he has occasion for, it neither does nor
can provide him with them as he has occasion for them. The greater part of
his occasional wants are supplied in the same manner as those of other
people, by treaty, by barter, and by purchase. With the money which one
man gives him he purchases food. The old clothes which another bestows
upon him he exchanges for other clothes which suit him better, or for
lodging, or for food, or for money, with which he can buy either food,
clothes, or lodging, as he has occasion.