The rule of the game is that a move, once played, cannot be overturned. As these things go, this seemingly arbitrary dictum is only a source of frustration to those who feel their winning hand was unfairly denied by a seemingly trivial misstep. Once the screaming and crying is over, it is worth asking whether the rule teaches one anything after all. Well, take no move for granted, most obviously. Perhaps as obviously, a game one can't lose doesn't deserve its name.