The Enchiridion by St. Augustine
Chapter 6.--Controversy Out of Place in a Handbook Like the Present.
Now you ask of me a handbook, that is, one that can be carried in the hand, not one to load your shelves. To return, then, to the three graces through which, as I have said, God should be worshipped -- faith, hope, and love: to state what are the true and proper objects of each of these is easy. But to defend this true doctrine against the assaults of those who hold an opposite opinion, requires much fuller and more elaborate instruction. And the true way to obtain this instruction is not to have a short treatise put into one's hands, but to have a great zeal kindled in one's heart.