Livre d'Or

True, although prophecies need not be things to be obeyed. In fact they're often at their worst when they are, since that's when they turn into an excuse to introduce random plot twists without having to think up any actual motivation. (I think The Malloreon is the worst case of this I know, since it basically stretches that principle out into a whole five-book series, but there are plenty of others.) The best kind of prophecies are the ones that say "this will happen whether you like it or not, perhaps even as a direct consequence of you trying to avoid it", which is much more about straight foreknowledge than moral authority.