When I hear another express an opinion which is not mine, I say to myself, he has a right to his opinion, as I to mine. Why should I question it? His error does me no injury, and shall I become a Don Quixote, to bring all men by force of argument to one opinion?...Be a listener only, keep within yourself, and endeavor to establish with yourself the habit of silence, especially in politics.

Memoirs, 4: Correspondence and Private Papers (ed. 1829)