R.C. Sproul Jr.:

If we would seek to preach to the mind, we also must encourage those in our hearing to receive the Word preached with their minds. The habits of their hearts will be shaped by the habits of their minds. If, strangely, they listen only to check the preacher's level of orthodoxy, if they seek only to have their intellects tickled, if they attend to preaching only that they might show forth their own erudition, it is not their minds but their egos that are not being preached to. Just as a deep and complex sermon, rather than a simple and straightforward one, can be a sign of a preacher getting in the way, a deep and complex analysis of a sermon by the adept layman can be a sign of a congregant getting in the way. Our minds always need to be exhorted to beware our propensity for ego.

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Quoted in Feed My Sheep: A Passionate Plea for Preaching. 2nd edition, 2008 by Reformation Trust Publishing, an imprint of Ligonier Ministries. Available here.