In my case, for instance, when I perform shugyou, ki naturally starts to flow, and Ki of Heaven and the Ki of Earth, spontaneously being produced, it feels like what has been described as
twin kami standing side by side, sweetly guiding my breath and my ki, water and fire [iki]. They manifest like the pictures: standing side-by-side to gently stir the breath and the ki, water and fire, in spirals.
So that, secluding yourself deep in the mountains, in mysterious valleys, when you pray, spontaneously ki is created and emitted. And in this way, the aiki of your own heart and deepest impulses gets hooked up – musubarete iku – to the aiki of Heaven and Earth. Which is to say that: the aiki of your soul gets hooked up to the resonance of the Universe, and when that happens, you unfailingly become capable of great things.
– – – O’Sensei, probably audio-recorded by by Masatake Fujita, transcribed by Sadateru Arikawa Shihan, published in Aiki-Shinzui, p. 89