Re: Transmission, Inheritance, Emulation 17
Young Takeda Sokaku learned from his father and was at the very least influenced by Kurokochi Dengoro Kanenori, if not taught. From a general glance, we can see at least sumo, kenjutsu, sojutsu, and jujutsu as part of what Takeda learned.
We can also see that Takeda had that quality of stubborn-ness which bordered on compulsive-obsessive behavior to exceed.
Then, we toss in learning from Sakakibara Kenkichi.
My thoughts are that the very beginnings of internal skills and aiki were started with his sumo training. From there, Takeda Sokaku could have learned other structural body skills from kenjutsu and sojutsu. It's my understanding (not proficiency) that you can't handle a spear or naginata efficiently without solid body structure. And so, Takeda Sokaku could have taken his internal training (which probably included some form of body structure) from sumo and modified it to work with the added body structure he learned from sword and spear.
From there, he could have designed, altered, and changed the training methodology to create something new and most likely better at instilling aiki.
What if the sumo training gave him a very good start but that it was the weapons work where he had to put all of his knowledge of the internal methods of the body ... out to the tip of a sword or spear that really got him hooked. With the way he approached training, it isn't too much of a surprise that he could have created a new way of training which was better and contained elements he learned from multiple systems.
What if the aiki that was taught to Sagawa, Kodo, Ueshiba, etc. was the sole creation of Takeda Sokaku?