Can we assume that Morihei Ueshiba might have also made a promise to his teacher, Sokaku Takeda, not to reveal the "secrets" of aiki to his students? A few talented ones, such as Tohei, have had to steal the "secrets" by thinking outside the box or cross-trained other disciplines.
I don't think anyone knows. We do know that Sokaku told people not to teach but one of two of their students. Tokimune said the same. Some on the net (not one of which are impressive) say -that- is misunderstood.
So lets see
Sokaku-: of thousands who trained with him -only a handful were known for unusual power and skill
Tokimune-openly stated in an interview the very same thing-to only teach one or two. All of that
would be conjecture and meaningless accept we see him teaching students for thirty years, some of whom were the president and secretary of his own organization, who did demos for all the big events, then he gives menkyo to Kondo and states he was the only one he taught real technique to. Tokimune's statement, and his actions are clear enough.I haven't felt or seen anyone from his school/style that impressed me as having it-it's all "Frankenstein like, one-step stiff jujutsu."
Sagawa-had one we know of
Kodo-has a few
Ueshiba- Who among his students is known for unusual power? Tohei and Shioda do not count, they went elsewhere and only AFTER that were they known to have gotten it.
Are there any hints on internal/solo trainings in that book?
Specifically? No. The fact that he mentions over and over like a mantra that the path to aiki is to change the body and "make an aiki body" and talks about training with heavy poles is worth everything to the smart reader. He wasn't talking about muscle. Just how was he building those connections in his body to absorb power from an opponent and project? In and of itself, that is something that is never talked about or is openly denied.
YMMV, I think its smart to feel and also watch the vast majority of those in the arts (regardless of rank and affiliation) and let their understanding and their opinions, speak for itself. I don't debate it on the net anymore. Ten thousand words of debate all end ...in person, Your understanding is in your own hands and all is made clear.
What and how, are you training, David?