Discourses, "Against or to Those Who Readily Tell Their Own Affairs" (§1)

“When a man has seemed to us to have talked with simplicity (candor) about his own affairs, how is it that at last we are ourselves also induced to discover to him our own secrets and we think this to be candid behavior? In the first place, because it seems unfair for a man to have listened to the affairs of his neighbor, and not to communicate to him also in turn our own affairs; next, because we think that we shall not present to them the appearance of candid men when we are silent about our own affairs.”