St. Augustine of Hippo (354-430 AD):
I bring no charge against the words which are like exquisite and precious vessels, but the wine of error is poured into them for us by drunken teachers….
Johann von Goethe of Weimar (1749-1832):
The man spoke with dignity and with a certain radiance on his face. This is what he said: “the duty of a teacher is not to preserve man from error, but to guide him in error, in fact to let him drink it in, in full draughts. That is the wisdom of teachers. For the man who only sips at error, can make do with it for quite a time, delighting in it as a rare pleasure. But a man who drinks it to the dregs, must recognize the error of his ways, unless he is mad.” 
Karl Kraus of Vienna (1874-1936):
A school without grades must have been concocted by someone who was drunk on non-alcoholic wine.
 Augustine, Aurelius. Saint Augustine – Confessions. Translated by Henry Chadwick. NY: Oxford UP. 1991. I, xvi (26), p. 19.
 Goethe, Wilhelm Meisters Lehrjahre. (Wilhelm Meister’s Apprenticeship.) 1795–96. Edited and Translated by Eric A. Blackall. NY: Suhrkamp Publishers. 1983. VII, ix, 302.
 Kraus, Karl. Half–truths & one–and–a–half truths: selected aphorisms. Edited and Translated by Harry Zohn. Engendra Press: Montreal. Reprint Chicago UP. 1976. p. 75.