I meant to post these 2 links on the thread as background about the way of the cross but they fit well here. They are discussion of Chinese qigong but seem to have a lot of similarity to what Ueshiba was saying. They discuss qigong as a path of "destiny". There seems to be two components, acting in accordance with the will of heaven and internal alchemy. Uniting heaven, earth and man (being a bridge between heaven and earth) is to act in accordance with the will of heaven and thereby act out one's will (actually heaven's will) in the world. In turn, practice of inner alchemy (qigong) will enable one to develop the will that creates changes in the world (or others) ie to be the sage that changes the world through non-action.
I think the second link is probably only readable after reading the first:
Chris, I am a little confused. You talk about standing on the bridge as being in the centre of the spiral between In and Yo but is that more a description of what happens when the two gods step down off the bridge and descend to earth? It doesn't seem to matter much, the way they circle around the land they have created seems a strong echo if not a direct retelling of the events on the bridge.
It might be clearer if you remember this passage from the first Floating Bridge of Heaven
It is said that Aikido is "Standing on the Floating Bridge of Heaven". The Floating Bridge of Heaven is the turning of fire and water bound together. Fire moves water, water is moved by fire. Fire and water are one thing. They turn in a spiral. They are entwined through Ki. That is something that is enacted through the breath ("iki"). This breath ("iki") is Aiki.
So...Izanagi and Izanami are In and Yo, fire and water turn in an interchanging spiral that forms the connection between heaven and earth - in other words, they're not quite synonymous, although they are closely related (if you think of it that way the diagram in Morihei Ueshiba and the Way of the Cross
may make more sense). Also, there's a pretty good basic summary here of the basic concepts: