Or, where and why did this stuff come about?
I'm suffering from blue balls, because I KNOW KARATE and I haven't been attacked in a while. I haven't had the chance to impress my girlfriend, earn accolades and the key to the city, rid the world of crime, etc...
So what is it?
There is a movement that appears in many shorin ryu kata and all over the korean world, shotokan, and no one likes to acknowledge that it exists, because it is a block, and it doesn't work. Raise your fist to your opposite ear and bring the arm down diagonally.
I don't know the Japanese name but it is a "downward block."
So why does this movement show up in so many kata, when it doesn't have any meaning. I've never seen it used in a boxing match, etc.. etc.. etc.. name your preferred violent sport or think about all the fist fights you've ever seen. You've probably never seen this movement ever used effectively if at all, and you're not going to demonstrate this movement to your teenage UFC savvy friends as a "high percentage" technique.
This block won't reverse a RNC, or prevent you from being punched in the face repeatedly by the guy who is punching you in the face.

But maybe it will.

If you use the movement, and not whatever bullschit technique you have been conditioned to think of it as.
This movement can be used to fukk someone up, in many ways.
Ancient Chinese secret.