I wanted to bring closer to this walk through Augustine's book with some final notes.
"Anyone who thinks that he has understood the divine scriptures or any part of them, but cannot by his understanding build up this double love of God and neighbor, has not yet succeeded in understanding them" (86).
This concept would seem to me to be the most important one in Book 1. All the ethical requirements of God for humanity are summed up in "love God, love neighbor." If we truly understood this double love command, then we would not even need the Scriptures to know how to live in this world, for everything the Scriptures command us are summed up in them.
Where I would critique Augustine is that he does not have a firm sense of historical meaning. Although we do not have full access to the original meanings of the books of the Bible, the most likely method to know them is not theological but historical-cultural. Augustine advocates a method that fiddles with the meanings of the biblical texts if they do not fit with the love of God or orthodoxy (the rule of faith). He is right about appropriation, but not about interpretation.
The texts meant what they meant in history. We can't change that. From a standpoint of truth, we best let them mean what they seem to have meant and then live in that tension. Augustine basically advocates a method of retrofitting the original meaning to suit his theology.
But Augustine is completely sound when it comes to appropriating the biblical texts. We must always appropriate them through the filter of Jesus' double love command.
"A person who is good and a true Christian should realize that truth belongs to the Lord, wherever it is found." (72)
Augustine deals with the clear passages of Scripture in Book 2. There is much that I believe needs critiqued in Book 2. He has an inferior understanding of how language works ("picture theory"). He will develop his method of "fiddling" with the interpretation of texts in Books 2 and 3. Book 2 deals with signs of which we are ignorant, Book 3 with signs that are ambiguous.
I have quoted above a theme that he follows through much of Book 2, namely, that there is validity in much study outside of the Bible, including knowledge gained from logic, history, and science. In the end of the Book, however, I think he approaches taking it away: "What a person learns independently of scripture is condemned there if it is harmful, but found there if it is useful" (151).
There are all sorts of caveats to the notion that "All truth is God's truth." But the basic principle is sound, even if the application is complicated. (Another key element in this Book, BTW, is Augustine's canon list, from the 390s before the Lateran Council of Carthage that set that NT canon for the West.)
First we must consult “the rule of faith, as it is perceived through the plainer passages of the scriptures and the authority of the church.” (3)
Book 3 deals with ambiguous texts in Scripture. Here we find the principle to let the clear passages interpret the unclear ones. From the standpoint of historical consciousness, again, this approach is pre-reflective. The texts meant what they meant in history. You cannot change the meaning of a text from one period by a text from another.
However, in the age of hermeneutics, we shift the principle to our appropriation of Scripture. We focus on texts that are "clear" in the light of Christian consensus.
It is more difficult to identify exactly how we can identify exactly what the contents of the "rule of faith" are. Augustine seems to follow a principle that looked to the most prominent churches of his day in Book 1. Someone might say, "the Bible is the rule of faith," but the function of the rule of faith is to help us know how to prioritize biblical material. So do we go with frequency, trajectory, centrality of the biblical teaching? How would we establish centrality?
Orthodoxy seems to require some sense of trajectory, especially on issues like the Trinity or the nature of Christ. The consensus of Christendom is a possible move here--what have the majority of Christians believed throughout the centuries? Formulating a biblical theology is a corporate, spiritual art that resists any easy or straightforward formula.
Book 4 is about the delivery of the word of God in preaching.
"It is the duty, then, of the interpreter and teacher of Holy Scripture, the defender of the true faith and the opponent of error, both to teach what is right and to refute what is wrong, and in the performance of this task to conciliate the hostile, to rouse the careless, and to tell the ignorant both what is occurring at present and what is probable in the future."
Clearly Augustine thinks that substance--both in content and in the person of the preacher--is more important than the style or form of delivery. But having said that, Augustine fully supports the use of good rhetoric in presentation. In keeping with the three forms of ancient rhetoric (forensic, epideictic, and deliberative), Augustine sees the three different goals of speech as to teach, to give pleasure, and persuasiveness. Good speaking in each case respectively are clarity, beauty, and persuasiveness.
Wisdom, he says, is more important than eloquence. He urges prayer before speaking, and indicates that the character of the preacher is important if there is hope for the audience to heed the words.
Perhaps the most controversial point he argues is that some biblical passages shouldn't be preached because they are difficult. This flies in the face of current thinking, but I think he has more of a case than you might think at first. For example, imprecatory psalms may show us that it is okay to be angry and I could see myself preaching from one, but the law of Christ suggests we should not dwell on them.