If you doubt you can accomplish something, then you can't accomplish it. You have to have confidence in your ability, and then be tough enough to follow through.
Rosalyn Carter
He that knows nothing, doubts nothing.
Proverb
A mind that questions everything, unless strong enough to bear the weight of its ignorance, risks questioning itself and being engulfed in doubt.
Emile Durkheim
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 certainties.
Francis Bacon
Don't waste life in doubts and fears; spend yourself on the work before you, well assured that the right performance of this hour's duties will be the best preparation for the hours and ages that will follow it.
Ralph Waldo Emerson
The basic stimulus to the intelligence is doubt, a feeling that the meaning of an experience is not self-evident.
Wystan Hugh Auden
Jealousy lives upon doubts, it becomes madness or ceases entirely as soon as we pass from doubt to certainty.
Francois de La Rochefoucauld
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 certainties.
Francis Bacon
Don't turn your back upon your doctrinal doubts and difficulties. Go up to them and examine them. Perhaps the ghastly object which looks to you in the twilight like a sheeted ghost may prove to be no more than a table-cloth hanging upon a hedge.
Andrew Kennedy Hutchison Boyd
Tonight's show is about doubt. Or maybe it isn't - haven't made my mind up yet.
Bill Bailey
Oh! let us never, never doubt What nobody is sure about!
Joseph Hilaire Pierre Ren Belloc
Materialists and madmen never have doubts.
Gilbert Keith Chesterton
Don't ever aim your doubt at yourself. Laugh at yourself, but don't doubt yourself.
Alan Alda