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.
 Adam Smith, The Theory of Moral Sentiments (1759). copy citation

Context

“In a class one day That selfishness was bound to pay? Of all doctrines that was the Pith. Wasn’t it, wasn’t it, wasn’t it, Smith? In contrast, the Moral Sentiments actually begins with the following observation: 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. . . . That we often derive sorrow from the sorrow of others, is of a matter of fact too obvious to require any instances to prove it; for this sentiment, like all the other original passions of human nature, is by no means confined to the virtuous and humane, though they perhaps may feel it with the most exquisite sensibility.” source