Nicene and Post-Nicene Fathers, Vol. II:
On Christian Doctrine: Chapter 8

Chapter 8.—The Obscurity of the Sacred Writers, Though Compatible with Eloquence, Not to Be Imitated by Christian Teachers.

22.  But although I take some examples of eloquence from those writings of theirs which there is no difficulty in understanding, we are not by any means to suppose that it is our duty to imitate them in those passages where, with a view to exercise and train the minds of their readers, and to break in upon the satiety and stimulate the zeal of those who are willing to learn, and with a view also to throw a veil over the minds of the godless either that they may be converted to piety or shut out from a knowledge of the mysteries, from one or other of these reasons they have expressed themselves with a useful and wholesome obscurity.  They have indeed expressed themselves in such a way that those who in after ages understood and explained them aright have in the Church of God obtained an esteem, not indeed equal to that with which they are themselves regarded, but coming next to it.  The expositors of these writers, then, ought not to express themselves in the same way, as if putting forward their expositions as of the same authority; but they ought in all their deliverances to make it their first and chief aim to be understood, using as far as possible such clearness of speech that either he will be very dull who does not understand them, or that if what they say should not be very easily or quickly understood, the reason will lie not in their manner of expression, but in the difficulty and subtilty of the matter they are trying to explain.