Shioda talked about it a lot, and quite clearly, as in "In order to generate Kokyu you must stand as if you are making your big toe sink into the surface of the ground." - he often spoke about the importance of bringing power from the ground. There's a video clip somewhere where he says it straight out, hesitates, and then changes the subject.
Ueshiba spoke about it in very classical Chinese terms, Heaven, Earth and Man. The basic model, using the same terms that Chinese arts to describe power from the ground, in the same contexts.
Daito-ryu folks talk about it too, as Keisetsu Yoshimaru points out in this article
, so I guess we know how it got to Ueshiba.
Yukiyoshi Sagawa, of course, thought that building the lower body and the legs particularly was important.
I've heard two of the senior Japanese students of Seigo Yamaguchi talk about the importance of keeping your intent on the bottom of your feet, for the same reasons.
So...the ground power is an important thing, but not the only thing. Of course, it's still nothing to sneeze at.
The first picture in Chris's new blog post (Morihei Ueshiba, Bruce Frantzis and Bagua) shows a typical bagua posture, where apparently "the knees are held together and the body is sitting while walking". In addition to that, to my mind, people in the chinese arts set the heels first on the ground.
In karate exist movements, where the knees tend to be held together but the body is not "sitting while walking" , both of the feet are turned to the inside and the bodyweight seems to be equally distributed over the soles of the feet.
The second aikido doshu tended to glide as much as possible on the balls of his feet.
Non of them, although all keep their bodies very much in good balance, seem to glide like Ueshiba Morihei, who, to my eyes, moves more like a traditional japanese dancer but even more freely, without posturing and nevertheless excellently balanced. Some people would describe his as natural movement but there I wouldn't agree either.
All have awareness of the ground.
Where is the difference? Degree? Zanshin? Is awareness of the ground increased for internal strength or is it the other way round?