I have written previously about Aiki principle, yet it is extremely subtle and easy to miss in our practice. It is necessary therefore to further clarify it and make it more easily accessible. O-sensei described it as Ame no Uki Hashi, "The Floating Bridge of Heaven.” In Shinto this is the divine cross of fire and water ki.
The principle of Aiki didn’t begin with O-sensei or even with Takeda Sokaku of Daito Ryu fame. It is at least five thousand years old and is the foundation of Chinese martial art, medicine, and philosophy. It begins with the statement ten-jin-chi, which indicates the vertical relationship between Heaven, Man, and Earth. This is the first manifestation of Aiki.
This vertical relationship is also called tate. It is water ki, the foundation of the physical world, standing up vertically. The horizontal line of the cross is called yoko. It is fire ki branching out from the vertical trunk or stem of the physical world. Fire ki is active and moves; water ki is passive and is moved. This active and passive relationship is essential to manifesting aiki in our movement.
Mankind moving through the center of this form gives it intention (Yi), which activates the cross to begin turning and create naname, the diagonal, or spiral form of the manifest world. This is what O-sensei referred to as Takemusu, the continual creation of new form, or technique born from the circumstances of the moment.
Practicing with these guidelines as our reference point, the secrets of aikido technique are gradually realized and we are transformed. This needs to be considered seriously. No amount of repetitive practice will reveal it.