Why we preach

Albert Mohler has done a three-part series on why we preach. (HT: Stronger Church).
Here's a sample:

The preacher is a commissioned agent whose task is to speak because God has spoken, because the preacher has been entrusted with the telling of the gospel of the Son who saves, and because God has promised the power of the Spirit as the seal and efficacy of the preacher's calling.

It's a strong, readable series: Part 1, Part 2, Part 3.