The Purpose of Preaching

When the people of God come to church every Sunday and hear the Word being preached, one may ask what the ultimate goal of preaching. Is it to get a 'spiritual' warm, sentimental feeling or relief from all sorts of psychological stress or entertainment that includes a few mentions of God in the background? Or is it to hear the wisdom of the preacher which flows from his personal interest, be it psychology, philosophy, sociology, pop culture, etc.? If that is the case, the pulpit becomes a stand-up talk show that boasts the wisdom of men aimed to please the audience. What then is the purpose of preaching?

"The Scottish preacher James Stewart put it like this: The aim of all genuine preaching are:
to quicken the conscience by the holiness of God,
to feed the mind with the truth of God,
to purge the imagination by the beauty of God,
to open the heart to the love of God,
to devote the will to the purpose of God."

(taken from John Piper, The Supremacy of God in Preaching, Revised Ed, Baker, 2004, p. 23).