Parsifal
Suddenly a wounded swan (a bird that is sacred to the knights of the Grail) falls dead at Gurnemanz’s feet.  The swan had been killed by Parsifal.  He did not know that it was a wrong thing to do, but when the knights capture him he realizes his guilt and he breaks the arrow.  The knights ask him his name, but Parsifal says he does not know his name or where he comes from.  Suddenly the knights realize that Parsifal is the pure fool they need who can capture the Holy Spear.