“How selfish soever man may be supposed, there are evidently some principles in his nature, which interest him in the fortune of others, and render their happiness necessary to him, though he derives nothing from it except the pleasure of seeing it.”

The book’s opening line lays the groundwork for all that follows. To that end, this single sentence serves two important purposes. First, it alerts the reader to one of Smith’s broader purposes, which is to rescue human nature from the cynical views of David Hume. Second, it hints at certain redeeming elements in that nature, the most important of which Smith identifies as “sympathy.”

“The sympathy, which my friends express with my joy, might, indeed, give me pleasure by enlivening that joy: but that which they express with my grief could give me none, if it served only to enliven that grief. Sympathy, however, enlivens joy and alleviates grief. It enlivens joy by presenting another source of satisfaction; and it alleviates grief by insinuating into the heart almost the only agreeable sensation which it is at that time capable of receiving.”

Sympathy, the central concept in Smith’s entire theory of moral sentiments, gives us pleasure in both joy and grief. In this case, it is the sympathy of friends, “the correspondence of the sentiments of others with our own,” that intensifies our joyous feelings and diminishes our sadness. Those who espouse a purely cynical view of human nature might attribute our desire for sympathy to mere “self-interest,” but “self-interest” cannot account for the motives of the friends who express sympathy.

“Originally, however, we approve of another man’s judgment, not as something useful, but as right, as accurate, as agreeable to truth and reality: and it is evident we attribute those qualities to it for no other reason but because we find that it agrees with our own.”

Sympathy denotes fellow feeling not only with the joys and sorrows of others but also with their ideas and conduct. In short, sympathy is the central concept in Smith’s entire theory because it is the basis of our moral judgments.