I finished The Supremacy of God in Preaching by John Piper last night. [For those of you who are wondering, some of the books I've finished were half-read and sitting on my bedside table, waiting for me to return. This is one of them.] I read this as part of my preparation for an essay I'm working on ("'Divine Light, Holy Heat': Jonathan Edwards, the Ministry of the Word, and Religious Affections").
I found this book particularly useful for that task; of course, the basic point that Piper makes--that preachers must delight in God as their supreme passion in order to preach in a way that moves others to delight in God--can be substantiated through Edwards' own writing. While his final chapter makes the case explicitly, I think we have an even better handle on this theme now than when the book was first written in 1993 because of the Yale edition of Edwards' works and the Yale online Jonathan Edwards Center manuscript project. I'm hoping to make this case in some detail for the paper.