1. From Invincible Warrior by John Stevens: Regarding Takeda, "His extraordinary ability was due to mind control, technical perfection honed in countless battles, and mastery of aiki, the blending of positive and negative energy."
2. Shirata: By means of the breath (iki) of the Heavens and the breath of the Earth, through the in and yo (yin and yang) the multitude of things has come to be born. The breath of the Heavens and the Earth is the abdomen of everyone, and when a person partakes of this breath the techniques of aiki are born, with and by means of the Positive and Negative Principles.
3. Michio Hikitsuchi: The Kojiki started from the birth of the universe. By studying this you will understand the true meaning of aikido. There were two gods Izanagi and Izanami, a couple from whom several other gods were born. Both of them mean the breath in and out (akatama and shirotama).
and
Everything comes like yin and yang. Izanagi is yang and heaven. Izanami is yin and heaven.
4. Henry Kono (Aikido Today Magazine; #31 Dec.93/ Jan. 94)
Interview of Henry Kono sensei by Virginia Mayhew and Susan Perry.
ATM: When you had conversations like these with O'sensei, what would you talk about?
HK: Well, I would usually ask him why the rest of us couldn't do what he could. there were many other teachers, all doing aikido. But he was doing it differently - doing something differently. His movement was so clean!
ATM: How would O'sensei answer your questions about what he was doing?
HK: He would say that I didn't understand yin and yang [in and yo]. So, now I've made it my life work to study yin and yang. That's what O'sensei told me to do.
ME: I think we can say that Takeda knew what yin/yang meant. I think we can say Shirata did, too. I'm not all that knowledgeable about Hikitsuchi, but it's a good guess he understood yin/yang. At least somewhat. When we get to Kono, he's asking questions. Good for him, btw. He's trying to find out how to do what Ueshiba does. But, he clearly doesn't understand yin/yang then. Not only that, but the really critical point that is inferred is that a lot of other teachers didn't understand yin/yang either.
What is it about yin/yang? Ueshiba references in/yo, ka/mi, Izanagi/Izanami, Izu/Mizu all the time. It was all his terminology for yin/yang. Contradictory forces. And yet, all those references of Ueshiba can be traced back to the body.
5. Ueshiba:
Put the active principle (yo) into the right hand
Turn the left into the passive (in)
And so guide the adversary
The Pine, the Bamboo, and the Plum
The make up of Ki that we are training to purify
From where do they arise?
The Water and Fire of the change in the self.
6. In an interview with Masando Sasaki, we read: I remember he got angry at me when I asked him, "Sensei, how should I explain when people ask me what aikido is?" (laughter) Hardly anyone had even heard of aikido back then, so I always had a hard time explaining it. I figured Ueshiba Sensei would be able to explain it since he was the one who created it. But when I asked him, he stamped the ground and exclaimed, "Aiki? I am aiki!"
7. Ueshiba: If you wish to apply Ki-no-Miyoyo from the foundation of this nen, be aware that the left side of the body will be the basis for Bu, while the right side will offer an opening for connection with the ki of the universe. When the links between left and right are complete, then one's movements become totally free.
ME: Change the body with in/yo. As stated previously, the book about Miyamoto Musashi talked about contradictory forces in the body. Morita Monjuro recalls (page 263) his experiences with training in kendo. He comes to the conclusion that there must be a cross body connection. The right foot along with the left hand. Then the left foot along with the right hand. He agains mentions diagonal forces on page 266.
Ueshiba talks about spirals winding up on the right and winding down on the left. He talks about the aiki cross. Ueshiba was training diagonal forces, or cross body connections.
We find that in/yo is part of the body. We find references to that in Transparent Power where Sagawa states boldly that aiki is a body training method.
8. In Transparent Power by Tatsuo Kimura: The elder Sagawa, who sometimes had a fiery temper, would take what he learned from Takeda and try it out on strong and mean-looking construction workers he came across. He quickly realized that if you lacked the sort of aiki that Sokaku Takeda possessed, none of the techniques would work against a persistent opponent. So Sagawa's father said to Takeda, "I'm already so old, I think it would be better if you'd teach me Aiki instead of techniques."
9. Mrs. Horikawa knew that aiki changed the body.
Stan Pranin talking about training and states, It's the idea of "stealing techniques with your eyes," isn't it?
Mrs. Horikawa replies, It's not with the eyes, it's with the body.