Augustine on preaching

"There are two things on which all interpretation of Scripture depends: the mode of ascertaining the proper meaning, and the mode of making known the meaning when it is ascertained." (Augustine, On Christian Doctrine, Book 1, Chapter 1, para 1).

"The author divides his work into two parts, one relating to the discovery, the other to the expression, of the true sense of Scripture. He shows that to discover the meaning we must attend both to things and to signs, as it is necessary to know what things we ought to teach to the Christian people, and also the signs of these things, that is, where the knowledge of these things is to be sought." (Preface to Augustine's On Christian Doctrine)