When someone opens up and talks honestly about their personal matters, why do we feel compelled to share our secrets with them too? Why do we think this is the honest thing to do? First, it feels unfair to listen to someone's private business without sharing our own in return. Second, we worry that staying quiet about our own affairs will make us look dishonest or closed off. You hear people say this all the time: "I told you everything about myself — won't you tell me anything about you?"
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. Indeed, men are often accustomed to say, I have told you all my affairs, will you tell me nothing of your own?