The only limit to our realisation of tomorrow will be the doubts of today.
Franklin D Roosevelt, US President (1882-1945)
Doubt is not a pleasant condition, but certainty is absurd.
François-Marie Arouet, known as Voltaire, French philosopher (1694-1778)
I love to doubt as well as know.
Durante degli Alighieri, known as Dante, Italian poet (1265-1321)
Tell people there are more than 300,000 billion stars in the universe and they will believe you without question. Tell them a porch railing has wet paint on it and they have to touch it to make sure.
If you would be a real seeker after truth, it is necessary that at least once in your life you doubt, as far as possible, all things.
René Descartes, French philosopher (1596-1650)
Our doubts are traitors and make us lose the good we oft might win, by fearing to attempt.
William Shakespeare, English playwright, poet (1564-1616)