Tim Keller has become a minor celebrity lately in the evangelical world with his book "Reason for God." What some people do not know is that he used to be a seminary professor. Among his courses was one on preaching. If one has ever heard Keller preach, one knows Keller knows his stuff on how to preach. RTS on itunes Univerity has recently posted the whole course that Keller taught with the late Edmund Clowney, free for download.