A Great Man, we said, was always sincere, as the first condition of him. But a man need not be great in order to be sincere; that is not the necessity of Nature and all Time, but only of certain corrupt unfortunate epochs of Time.
 Thomas Carlyle, On Heroes, Hero-Worship, and The Heroic in History (1841). copy citation

Context

“For observe one thing, a thing too often left out of view, or rather altogether lost sight of in this controversy: That it is not necessary a man should himself have discovered the truth he is to believe in, and never so sincerely to believe in. A Great Man, we said, was always sincere, as the first condition of him. But a man need not be great in order to be sincere; that is not the necessity of Nature and all Time, but only of certain corrupt unfortunate epochs of Time. A man can believe, and make his own, in the most genuine way, what he has received from another;—and with boundless gratitude to that other! The merit of originality is not novelty; it is sincerity. The believing man is the original man; whatsoever he believes, he believes it for himself, not for another.” source