One of these causes is the fact that believers and unbelievers alike are firmly persuaded that they have understood Christ's teaching a long time, and that they understand it so fully, indubitably, and conclusively that it can have no other significance than the one they attribute to it. And the reason of this conviction is that the false interpretation and consequent misapprehension of the Gospel is an error of such long standing. Even the strongest current of water cannot add a drop to a cup which is already full.

The most difficult subjects can be explained to the most slow-witted man if he has not formed any idea of them already; but the simplest thing cannot be made clear to the most intelligent man if he is firmly persuaded that he knows already, without a shadow of doubt, what is laid before him.