OE

Pith. A “probing questioner” is looking for the central point of a matter. That it is an “intellectual matter” suggests a word other than emotions for the blank, as does that choice's failure to relate to the “probing questioner” clue. Periphery is the opposite of central. Examination doesn't fit at all. Academics is a theme trap. The only answer that means “core or central point” is pith.