Two left-handed gloves don't make a pair. Two half-truths don't make a truth.
(Multatuli [Eduard Douwer Dekker] (1820-1887), Dutch writer, civil servant. "Idee 2," The Oyster and the Eagle: Selected Aphorisms and Parables of Multatuli (1872), trans. by E. M. Beekman, U of Mass. Press (1974).)
Belief in the truth commences with the doubting of all those "truths" we once believed.
(Friedrich Nietzsche (1844-1900), German philosopher, classical scholar, critic of culture. Friedrich Nietzsche, Sämtliche Werke: Kritische Studienausgabe, vol. 2, p. 387, eds. Giorgio Colli and Mazzino Montinari, Berlin, de Gruyter (1980). Mixed Opinions and Maxims, aphorism 20, "Truth Will Have No Other Gods Alongside It," (1879).)