On several occasions I've come across Russell's account of his decision that Wittgenstein was not a "complete idiot", but I've never been able to figure out what Wittgenstein wrote to him or what that one sentence was. Can anyone tell me?
Here's a quote from Russell's Collected Papers:
[Wittgenstein] was queer, and his notions seemed to me odd, so that for a whole term I could not make up my mind whether he was a man of genius or merely an eccentric. At the end of his first term at Cambridge he came to me and said: “Will you please tell me whether I am a complete idiot or not?” I replied, “My dear fellow, I don’t know. Why are you asking me?” He said, “Because, if I am a complete idiot, I shall become an aeronaut; but, if not, I shall become a philosopher.” I told him to write me something during the vacation on some philosophical subject and I would then tell him whether he was complete idiot or not. At the beginning of the following term he brought me the fulfillment of this suggestion. After reading only one sentence, I said to him: “No, you must not become an aeronaut.” And he didn’t.