Le doute n’est pas un état bien agréable,
mais l’assurance est un état ridicule.
Doubt is not a pleasant condition, but certainty is an absurd one.
François-Marie Arouet (Voltaire), Letter to Frederick William, Prince of Prussia (November 28, 1770). English: in S.G. Tallentyre (ed.), Voltaire in His Letters (1919), p. 232.