In the beginning of his career as a rabbi, Rabbi Naftoli of Ropshitz was once asked to speak when he was unprepared.  He told his audience, “When delivering a lecture it is proper to state the truth, to speak concisely and the topic should be in reference to the weekly portion.  I do not have anything to say on this week’s portion.  This is true; it is concise; and it is a comment on the weekly portion.” ~ Ohel Naftoli as quoted by R’ Zellig Pliskin