Such is the intellect's purpose, to grasp the standards and criteria whereby truth can be distinguished from error. Often it is intimated that truth is afraid of error. In the tradition of Thomas Aquinas, of course, just the opposite is the case. We do not know the truth until we can identify and explain accurately the arguments against the truth of any order, including that which claims there is no truth. Knowledge of truth includes knowledge of error.
Truth is the conformity of mind with reality.
Thus, if we doubt our own knowing faculty, we will never know the truth. If we think the world an illusion, nothing exists to which we can conform ourselves. If we hold that it is only our mind that imposes order on a chaotic world, we will remain locked into ourselves. Thus, to butt up against a reality that does not conform to the vagaries of a mind filled only with itself is a very healthy experience. This remarkable passage suggests that noodles and brains become weary and tired when they are not constantly refreshed with a reality that did not arise in themselves.