Re: Martial, spiritual, and jujutsu (split off from Funakogi Thread)
Ah, now we are getting somewhere.
I personally distinguish Aiki an Ju by physical relation. I believe Aiki can be used without any physical contact, where Ju must be in contact with a direct force.
For example, I would say musicians playing music together are exhibiting a kind of Aiki. The music coming from their instruments (Ki) is working together to make a harmony (Ai). There is not a physical interaction between the musicians yet they are forming a harmony with the energy they are releasing.
Ju requires a physical force to be applied. For example a balloon has the quality of ju. If you push on it, it will yield to your force, yet as soon as the force is removed it will spring back into place, or move around the force.
Martially this can be seen: with Aiki I lead your mind with my mind, making you over extend yourself and become unbalanced; with Ju I physically stick to you, following you physically, applying force where you are weak and unbalancing you.