No man likes to have his intelligence or good faith questioned, especially if he has doubts about it himself.
If a man will begin with certainties, he shall end in doubts; but if he will be content to begin with doubts, he shall end in certainty.
Our achievements speak for themselves. What we have to keep track of are our failures, discouragements, and doubts. We tend to forget the past difficulties, the many false starts, and the painful groping.
Doubt thou the stars are fire;
Doubt that the sun doth move;
Doubt truth to be a liar;
But never doubt I love.