Many years ago I ran across a column in Christianity Today called “What They Didn’t Tell You at Seminary Graduation.” Among the humorous aphorisms was this gem:
“Fifty-one Sundays of the year, preach so that the youngest child in your congregation can understand you. The fifty-second Sunday, preach so that the Ph.D., the Th.D., the Ed.D., and the M.D. are bewildered, awestruck, or filled with wonderment.”
That sounds about right to me, especially the first part.