Virtually all features of Adam Smith's moral theory can be found in elementary form in the first three chapters of The Theory of Moral Sentiments. One finds there discussions of natural human sympathy, of what I shall call the “impartial spectator procedure,” and of central aspects of Smith's conception of human nature; one finds references to the general rules of morality that guide the human conscience; and one finds hints of Smith's account of human passions that become clear only after one has read the rest of the book. In both TMS and his other central work, An Inquiry into the Nature and Causes of the Wealth of Nations, Smith begins with what he thinks is the central idea of the book: the first chapter of TMS is “Of Sympathy”; the first chapter of WN is “Of the Division of Labor.” The remainders of both of Smith's books are in large part elaborations and extensions of the ideas brought out in rudimentary form in those first short chapters.
The Theory of Moral Sentiments went through six editions during Smith's lifetime, the second and sixth receiving significant revision. The sixth edition, which was published only months before Smith's death in 1790, represents his most mature thought on the subject. He had had thirty-one years to reconsider his original examination since its first publication in 1759, and fifteen years since the publication of WN in 1776.