When the mind fully penetrates the body and ki and is in constant harmony with them, we can seek to understand six harmonies and other things related to dantien, etc. But finally, we get to the old saying that the mind leads the ki and the ki leads the body.
Anyway, after all is said and done, right or wrong, I have to go back to the words of Richard Kim, menkyo kaiden in daito ryu from Yoshida Kotaro. Paraphrased, Kim said something like, "It all comes down to the moment when you give your opponent your best shot and it either ends the fight or it doesn't phase him."
The whole purpose of budo is to ensure that the person of "do" remains safe and secure and that the irrational attacker is locked down immobile to be dealt with by proper authority. Well, or dead, if there is no other way. Mochizuki Sensei stressed that we must do no more harm than necessary to stop the attack. But the truth is, we have to stop an attack. Our metric of success is first: no injury to us or to the ones we defend. Second: as little injury as possible to the attacker. It is very good to think of having no enemy, but pathetic to have to maintain that delusion after the attacker kills your loved one. This is not to focus on killing but to make absolutely clear the continuum. Carpenters and masons use "level" as their prime reference for everything in the world. It exists on a continuum from "level" (exactly horizontal to gravity) to "plumb" (exactly vertical in gravity). Foundations must be level and walls must be plumb, but there are uses for every degree of variation between level and plumb. inclines for walking, "fall" for site drainage, pitch for roof angle. We cannot know only "level" to measure the world. We must understand and be able to work with the proper techniques for every angle and purpose.
So in budo, we work on a continuum from perfect universal peace and passive, relaxed stillness to decisive end of violence through physical and personal response. Because we are first decent people whose kokoro responds to love and generosity with love and gratitude and we love our families and peaceful times; and second, rational people who act for reasonable purposes, we always want peace. But we must understand that we are on that continuum. When one's own dignity and freedom or that of one's loved ones, or the innocent stranger are too severely impinged, it is unnatural simply to allow it. That is why laws arose, but budo arose from lack of law as individuals formed the Japanese society and created sumo, jujutsu and kenjutsu for actual fighting (bujutsu). Budo evolved out of bujutsu as a way for strong fighters to become moral leaders of strong fighters. These were the deepest and most spiritual of the fighters--not intellectuals with weak bodies, but hardened fighters who saw the need for a moral path in human life. Just as "level" is useless without "plumb," though, they knew that "peace" is useless without justice. You can live in "peace" under a terrible ruler, but it's not really peace. The entire environment must be somewhat subdued for real peace even to be possible. One can attain deep peace even in bad times, but it remains incomplete when the environment is at war.
Obviously, one can't go out and subdue the entire environment, though it makes for good (or at least sometimes funny) cinema. Or, anyway, one can't subdue the entire environment by force or violence. I think the best way is to remain strong, aware and friendly to everyone in my neighborhood. However, strange things happen in neighborhoods, often with people passing through. When such people (or even our neighbors) get an idea to push someone around, we have to be peacemakers. Mochizuki Sensei had a commendation from the Prime Minister of Japan for negotiating with the students occupying Tokyo University in the 1960s. And that's not code for "beating the stew out of the students." He talked with them. He used to tell me how he protected cities from Communist attacks in Mongolia during the war by helping the rural people outside the cities. This is how budo works.
But: when the rubber meets the road (as Kim might have said), it all comes down to that moment when the bully attacks you and you give him your best shot. Who will be left standing?
If you like to use the term "budo," you need to know this means training in such a way as to assure that your best shot will put the attacker down (even if that means just holding him in sankyo). You don't do more than necessary to stop him, but whatever you do must work. Those are the level and plumb of budo.
From there, budo becomes not only a collection of techniques that we "learn" by repeating them in dance fashion, but a vast ocean of technique and method, from aikido, judo, karate, jujutsu, boxing, wrestling, fencing, savage, xing yi, tai chi, bagua, shoaling and dirty criminal street tactics. Everything from horizontal to vertical and back, both above and below the earth.
And the last point is that IP/IS is a deep place in budo training where we learn to get closer and closer to delivering 100% of your effort to the place we intend it to apply.
When we say we direct our ki to our hand, we're thinking of making the hand light to move but heavy to hit. We don't put the ki into the hand so we can hit the attacker with our ki, but to activate not only the hand but the whole bodypath from grounded foot to the hand. Then when the hand hits the attacker (or we apply sankyo), we have the effect Shioda called shuuchu ryoku or "concentrated power." And I never saw anyone of any size fail to go down if Shioda hit them. Indeed, I don't think anyone ever saw Shioda really "hit" anyone except maybe a few times he mentions in his autobiography.
Anyway, hitting, throwing, holding are all the same in aikido, as much as that can be forgotten.
But the purpose of all the IP/IS/IT, as I understand it, is to be able to use the intrinsic qualities of the upright body to deliver maximum possible power with absolute minimal exertion.
Letting the muscles ease into tanren strength and letting the ki lead the body are ways to make the whole body congruent and martially effective. The mental/ki efforts are demanding but they are probably the essence of the deepest meditation. Peace without strength is irresponsible and is not budo.
Finally, IP/IS was not part of the techniques of aikido as I learned them but I felt its subtle presence in the aikido, judo and karate at the yoseikan. I, unfortunately, mistook that for conventional western athletic strength and I tried to achieve it by harder and harder muscular training (trying to use no strength in my aikido technique, however). If I had only know then...