Deep into that darkness peering, long I stood there, wondering, fearing, doubting, dreaming dreams no mortal ever dared to dream before. Edgar Allan Poe
By doubting we are led to question, by questioning we arrive at the truth. Peter Abelard
I am content with nothing, restless and ambitious... and I despise myself for the vanity, which formed half the stimulus to my exertions. Oh would that I were one of those plodding wise fools who having once set their hand to the plough go on nothing doubting. Thomas Huxley
The key to wisdom is this - constant and frequent questioning, for by doubting we are led to question and by questioning we arrive at the truth. Peter Abelard
The world is made up for the most part of morons and natural tyrants, sure of themselves, strong in their own opinions, never doubting anything. Clarence Darrow