Pain was something we were expected to endure. But I doubt very much if you would be entirely happy today if a doctor threw a towel in your face and jumped on you with a knife.
Roald Dahl

You will certainly not doubt the necessity of studying astronomy and physics, if you are desirous of comprehending the relation between the world and Providence as it is in reality, and not according to imagination.
Maimonides

The trouble with the world is that the stupid are cocksure and the intelligent are full of doubt.
Bertrand Russell

The first test of a truly great man is his humility. By humility I don't mean doubt of his powers or hesitation in speaking his opinion, but merely an understanding of the relationship of what he can say and what he can do.
John Ruskin

Nearly all the powerful people of this age are unbelievers, the best of them in doubt and misery, the most in plodding hesitation, doing as well as they can, what practical work lies at hand.
John Ruskin

Argument is conclusive, but it does not remove doubt, so that the mind may rest in the sure knowledge of the truth, unless it finds it by the method of experiment.
Roger Bacon

I think we ought always to entertain our opinions with some measure of doubt. I shouldn't wish people dogmatically to believe any philosophy, not even mine.
Bertrand Russell

Faith means belief in something concerning which doubt is theoretically possible.
William James

You have a class of investors and you have a class of speculators. The speculators historically haven't been big enough to cause the investors to doubt the long-term vision of stock.
Jim Cramer

A woman will doubt everything you say except it be compliments to herself.
Elbert Hubbard

I doubt if you can have a truly wild party without liquor.
Carl Sandburg

Doubt, of whatever kind, can be ended by action alone.
Thomas Carlyle

If you are ever in doubt as to whether to kiss a pretty girl, always give her the benefit of the doubt.
Thomas Carlyle

Doubt is to certainty as neurosis is to psychosis. The neurotic is in doubt and has fears about persons and things; the psychotic has convictions and makes claims about them. In short, the neurotic has problems, the psychotic has solutions.
Thomas Szasz

Life is doubt, and faith without doubt is nothing but death.
Miguel de Unamuno

Faith which does not doubt is dead faith.
Miguel de Unamuno

True science teaches, above all, to doubt and to be ignorant.
Miguel de Unamuno

Action and faith enslave thought, both of them in order not be troubled or inconvenienced by reflection, criticism, and doubt.
Henri Frederic Amiel

Ever since I became a Muslim, I've had to deal with attempts to damage my reputation and countless insinuations seeking to cast doubt on my character and trying to connect me to causes which I do not subscribe to.
Cat Stevens

I slept with faith and found a corpse in my arms on awakening; I drank and danced all night with doubt and found her a virgin in the morning.
Aleister Crowley