There is a difference between a sermon, on the one hand, and a lecture or essay on the other. A sermon is not simply a public address on a religious subject; it is not simply an exposition of a passage of Scripture. It is these things, yet if really is a sermon and not a lecture, it is something else too. It is a means by which God himself speaks to us. This is not an event the preacher can command or arrange. It is independent of his learning, his eloquence, his enthusiasm. But it does happen, and it is the only raison d’etre of preaching.