The man who cannot believe in himself cannot believe in anything else. The basis of all integrity and character is whatever faith we have in our own integrity.

Smith’s aphorism links moral reliability to an inner act of trust: the capacity to believe one’s own word and motives. If a person is chronically unsure of his own honesty or steadiness, then every outward commitment—religious faith, loyalty to others, civic duty—rests on unstable ground, because it depends on a self that cannot be relied upon. The second sentence sharpens the point: “integrity” is not merely a public reputation but a private conviction that one can and will act rightly. In this view, character is built from self-trust disciplined by conscience; without it, belief becomes performative, easily abandoned when pressure or temptation arrives.