Inconceivable

I recently had a conversation with Vester Hughes, the name partner at my law firm, in which he was moved to recall a story from his law school days at Harvard in the early 1950s. He was taking a class with professor Austin Scott, who was then in his 70s and always wore a vest. One day, Scott responded to a student's remark by saying:

Inconceivable. Inconceivable. Well, actually, it IS conceivable, because you just conceived of it. But it SHOULD have been inconceivable.