An Aikido master, according to the teachings, can't be beaten.

Nor can he be fought.

Aikido concerns itself with much more than martial arts, for those of you who didn't know. But I won't get into all of Aikido here. The point is that by the time you reach the status of Master in Aikido, you have not only learned all that kick-ass fighting and whatnot, you've learned that you are One with the Universe.

No shit; that's actually a requirement.

An Aikido Master (and this may hold true in other Arts, but Aikido's the easiest for me to talk about) can not be beaten because he moves and lives in Harmony with the Universe. You and I are parts of the Universe; we can't conceivably go up against it--literally. Not only can't you BEAT someone who's One With Everything, you CAN'T EVEN FIGHT THEM. Once you've decided to fight someone who always works in concert with the Whole of Everything, you've already lost, see? Aikido claims a literal and physical interpretation of this concept, by saying that neither you nor I, no matter how much we wanted to or tried, could even fight against a Master.

Besides ringing decidedly Zen in the ears, this whole things reminds me of Neo from The Matrix.
It also gives me strange ideas about what Enlightenment must be like.