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 chuses to depend chiefly upon the benevolence of his fellow citizens.
The use of the term self-interest has the connotation of selfishness, but Smith was not being hard-hearted. He was rather acknowledging that self connects with self in the modern world of commerce. His arguments for free trade were based not on the ruthlessness with which that term is now often associated. Smith believed that an open market -- free of guild regulations, which restrict labor and regulate prices, to the detriment of the public; free of special interests that through political means try to bend legislation to their own narrow advantage; free of lobbying; free of monopoly protection; and so on -- would be fairer, especially to the poorer classes who, especially in 18th-century France, were shackled by feudal restrictions. In an open market, we would instead negotiate for our fair "worth."
Worth here is economic, although there is naturally a moral sense, which Smith sought to ground in The Theory of Moral Sentiments, a book that is not about economics, but instead concerns the nature of relations between individuals in a secular society. Smith doesn't use that phrase, but he was writing about world in which everyday transactions would be guided by a new etiquette, one not derived from religious norms. As Emma Rothschild writes in her book Economic Sentiments "The traffic or commerce of modern life was ... a traffic in opinions." Her book is an examination of Smith and Condorcet and is concerned, as she writes, with the "discursive, reflective, self-conscious disposition, [which] is both a cause and a consequence of economic progress" (9). For Smith, the progress of affluence produced by commerce enfranchises opinions and sentiments. The negotiation in the market and in society are dependent on discourse.
Finally I am getting around to world literature, which is about the negotiations and discourse. Stay tuned.