The author, having discussed in the preceding book the method of dealing with unknown signs, goes on in this third book to treat of ambiguous signs. Such signs may be either direct or figurative. In the case of direct signs ambiguity may arise from the punctuation, the pronunciation, or the doubtful signification of the words, and is to be resolved by attention to the context, a comparison of translations, or a reference to the original tongue. In the case of figurative signs we need to guard against two mistakes: -- 1. the interpreting literal expressions figuratively; 2. the interpreting figurative expressions literally. The author lays down rules by which we may decide whether an expression is literal or figurative; the general rule being, that whatever can be shown to be in its literal sense inconsistent either with purity of life or correctness of doctrine must be taken figuratively. He then goes on to lay down rules for the interpretation of expressions which have been proved to be figurative; the general principle being, that no interpretation can be true which does not promote the love of God and the love of man. The author then proceeds to expound and illustrate the seven rules of Tichonius the Donatist, which he commends to the attention of the student of Holy Scripture.