The sole philosophy open to those who doubt the possibility of truth is absolute silence--even mental. That is to say, as Aristotle points out, such men must make themselves vegetables. No doubt reason often errs, especially in the highest matters, and, as Cicero said long ago, there is no nonsense in the world which has not found some philosopher to maintain it, so difficult is it to attain truth. But it is the error of cowards to mistake a difficulty for an impossibility.
Jacques Maritain, An Introduction to Philosophy, Sheed and Ward (New York: 1933) p. 181.