In two previous posts (part 1 and part 2), I have proposed that the traditional two-fold structure of meaning and significance, be made made a three-fold structure of meaning, implication, and significance.* (Hirsch included implication in meaning as do many, but a new book by Robert H. Stein reviewed here apparently makes this same three-fold distinction that I have offered.)
In a nutshell, meaning is what the human author intended to communicate. Implications are those things which are inherently connected with the author’s intention, but outside of his conscious thought and intention. Significance is the application of meaning and implication to any situation to which it might relate.
So here’s why I think this matters.
In Hirsch’s two-fold division, you end up with human authors “meaning” things that they have no knowledge of, much less intention of. In other words, an author “speaks better than he knows;” he has an unintentional intention. The passage’s meaning is then no longer subject to exegesis based on intent, since the meaning cannot be drawn out from the words the author used to communicate his intended message. If it’s in the words, it is separate from the author’s intent in context, in which case normal exegesis cannot draw it out, and which opens a rather large barn door to a text meaning anything at all (since the author’s intent is no longer controlling; future implications are of the reader’s world, not the author’s). The historical part of literal-grammatical-historical interpretation has reduced significance (no pun intended).
This problem has been answered in a number of ways, primarily some form of sensus plenior, the idea that there is a “deeper meaning, intended by God but not clearly intended by the human author, that is seen to exist in the words of Scripture when they are studied in the light of further revelation or of development in the understanding of revelation.”
While there are a number of problems with sensus plenior, but a major one is that it removes the possibility of exegesis of a text to arrive at the complete meaning, because the meaning is no longer in the words as the author used them to communicate to his readers. The fuller meaning is found in later words by different authors in different historical contexts, which which the original readers would not have had, and could not have known. Typically, this fuller meaning is found in the canonical context, which means the whole text of Scripture.
This is where the category of implication is helpful. It allows for there to be truth in a text that is not part of meaning. These implications are seen in later revelation, but they are not what the author meant his original readers to understand and respond to (which is what meaning must be connected to: what did the original author intend his original readers to understand, believe, or do in their lives at that time as a result of this text, including antecedent revelation).
Simply put, this means that God, the divine author (who knows all implications exhaustively) inspires the human author (who knows much less) to write a particular message to a particular audience. The human author then writes with a particular goal of informing or persuading his readers based on a truth that he is communicating. By intending something, he is not intending other things, and he is intending to not communicate still others things.
The divine author, aware of all the truth inherent in a given message (implications), also knows the full canonical context prior to the writing of the entire canon. He knows how the text lays a foundation for later revelation. In other words he knows what the implications are because he (and he alone) knows how those words will be used in generations to come.
So acknowledging a category of implication—those things which God knows and which the human author is not consciously intending—protects the integrity of the text and the author from “speaking better than he knew.” It also protects the later understanding of the text by showing how something can have truth that is ‘hidden.’ It also means that the human author and divine author can have the same meaning.
With this three-fold distinction, we can actually exegete the passages based on the traditional literal-grammatical-historical hermeneutic. This takes into account what the original author intended his original readers to understand, based on the language and syntax he used at the time of writing. We can focus on what it says, rather than what else it might say.
Having done the exegetical work, we can then turn to the canonical context to see what implications this passage might contain that later come to fuller flower. We can also speak of how the truth of the text lays a foundation for later revelation in the canon of Scripture yet to be revealed, or how the text might be typological or analogical. These implications can then be preached as eternal truth because of the canonical context.
Having then done the exegetical and canonical, or biblical-theological work, we can turn to the homiletical work of application, of presenting the “world in front of the text” that the listener should inhabit having listened to the text (cf. Kuruvilla, Text to Praxis, esp. 24ff.)
So we can preach what the text meant in its original context. We can preach how the truth of text lays the foundation for the work of God in subsequent history. And we can apply the the text to the hearers by using both the meaning and the implications as the ground of significance.
 Raymond E. Brown, “Hermeneutics,” in The Jerome Biblical Commentary, ed. Raymond E. Brown, Joseph A. Fitzmeyer, and Roland E. Murphy (Englewood Cliffs: Prentice-Hall, 1968), p. 616.