You won't find anything.
Aiki is a method, resolving in yo within and without you.
It is more complex than the typical nonsense of doing things; like timing and power displays between you and an attacker.
Aiki begins in you, is perfected within you, otherwise everything you try to do with an opponent that creates kuzushi on contact will fail.
The type of strength produced is not what most people understand and or know how to develop, and for that matter know how to cope with. The dilapidated state of Sagawa-where he couldn't open a jar-is not a requirement. Most people I meet still have this weird notion that "soft" means evading or running away.
a) that is not soft, and it is unsupported
b) it does not exhibit yin yang
They just don't know how to produce power without flexing muscle, so they opt for that evading stuff and call that "Soft."
Interestingly, and in keeping with the tenor of the thread, the world outside of aikido, has tracked that type of understanding for hundreds of years and have discredited it as ...not being part of the "soft" arts. They also recognized that it was low level, that many can do it- as it requires no serious training or changing of the body. The changing of the body is the cornerstone of the soft arts and here we go again why O sensei said no one can do what I do, because you do not understand In yo ho.
Just back from beer misogi in the hot tub - since I have not been able to do that for about six weeks since my foot injuries, it felt good! - anyway, I am enlightened now
IMO, there are two domains involved with an interaction - internal and external. I see soft as a joining of the external within the internal self and then self leads from there and there is no more external, it is all one within self, and of course, self has to be balanced, and that is where in-yo ho comes into play. Sorry, if I am coming across somewhat esoteric, but I did just say I have been enlightened in the hot tub
In other words, Nage receives the attack and connects to Uke's center and then leads both by moving himself with NO muscle tension - he does not dance around Uke by sliding or shifting with the energy in an external manner.
Sounds pretty neat, let's see if we can come up a Japanese term to describe that - OK, I got it, since it is a joining inside (which is Nage) let's start with Ai, and since it is joining with external energy, let's call that Ki - so, how about Aiki? and if you want to make it into a way of life, how about Aikido