There are two threats to reason, the opinion that one knows the truth about the most important things and the opinion that there is no truth about them. Both of these opinions are fatal to philosophy; the first asserts that the quest for truth is unnecessary, while the second asserts that it is impossible. The Socratic knowledge of ignorance, which I take to be the beginning point of all philosophy, defines the sensible middle ground between two extremes.

Western Civ, p. 18. - Giants and Dwarfs (1990)