What did Wittgenstein write on a note to Bertrand Russell?

Ludwig Wittgenstein (1889-1951) first worked as an engineer designing propellers. His application to study under Bertrand Russell at Cambridge involved an interview with the great philosopher in which Wittgenstein simply handed him a piece of paper containing a single short sentence. Russell read the sentence and took him on immediately. No one knows what it was that Wittgenstein wrote.

If you were Bertrand Russell, what sentence would make you accept a student?