Doubt is long-winded. Certainty is brief.

Of course I doubt. I do not practice a certainty. I practice a faith.

— Robert Breault

“In order to determine whether we can know anything with certainty, we first have to doubt everything we know”

— Anonymous

[Friedrich] Nietzsche said something marvellous, he said "Madness is not a consequence of uncertainty but of certainty", and this is fanaticism.

— Elie Wiesel

What I need most of all is certainty.

— Milan Kundera

That which is true must always remain true, though the applications may change greatly from generation to generation. It is the absence of such…

— Anonymous

I believe that we do not know anything for certain, but everything probably.

— Christiaan Huygens

Living by faith isn't living with certainty. It's trusting God in spite of unanswered questions and unresolved doubts.

— Rick Warren

“In this world, what is here is not necessarily here, and what is now may not really be now: place and time are malleable,…

— Amir Aczel

“Though what could anyone really say these days with one hundred percent certainty?”

— Garth Risk Hallberg

Go for broke. Always try and do too much. Dispense with safety nets. Take a deep breath before you begin talking. Aim for the…

— Salman Rushdie

Uncertainty is the only certainty there is, and knowing how to live with insecurity is the only security

— John Allen Paulos

Criticism, though dignified from the earliest ages by the labours of men eminent for knowledge and sagacity, has not yet attained the certainty and…

— Samuel Johnson

[I]f in other sciences we should arrive at certainty without doubt and truth without error, it behooves us to place the foundations of knowledge…

— Roger Bacon

As a businessman, I know that businesses need certainty.

— Bill Foster

“If you do not know what you want, it is a certainty you will never get it.”

— J. Helen Elza