Most philosophers will grant that on some issues and in some circumstances, we can acquire knowledge from another. But when it comes to moral knowledge, the presumption is on the side of autonomy; we must not rely on others for our moral beliefs. I argue here for the surprising thesis that in some circumstances we must rely on others in order to acquire moral knowledge. I believe that this, or something trivially different, is a position that Leibniz would hold. When woven together, his comments on teaching, authority, errors of conscience, and testimony provide concrescent support for this surprising thesis.