We can venture to express more emotion in the presence of a friend than in that of a stranger, because we expect more indulgence from the one than from the other.
 Adam Smith, The Theory of Moral Sentiments (1759). copy citation

Context

“The person principally concerned is sensible of this; and being assured of the equity of his judges, indulges himself in stronger expressions of passion, and is less afraid of exposing himself to their contempt by the violence of his emotions. We can venture to express more emotion in the presence of a friend than in that of a stranger, because we expect more indulgence from the one than from the other. And in the same manner the rules of decorum among civilized nations, admit of a more animated behaviour, than is approved of among barbarians. The first converse together with the openness of friends;” source