19.

You see what a long letter I have written. If, therefore, anything perplexes you, and you regard it of sufficient importance to be discussed between us, let not yourself be straitened by keeping within the bounds of ordinary letters; for you know as well as any one what long letters the ancients wrote when they were treating of any subject which they were not able briefly to explain. And even if the custom of authors in other departments of literature had been different, the authority of Christian writers, whose example has a worthier claim upon our imitation, might be set before us. Observe, therefore, the length of the apostolic epistles, and of the commentaries written on these divine oracles, and do not hesitate either to ask many questions if you have many difficulties, or to handle more fully the questions which you propound, in order that, in so far as it can be achieved with such abilities as we possess, there may remain no cloud of doubt to obscure the light of truth.