Peter A Goldsbury
First of all, Stefan, all good wishes for Christmas and the New Year!
'Physical' and 'spiritual' might be convenient opposites in English, but there is much ambiguity here, as might be gathered by making a clear and sharp distinction between mental events, physical processes, and so-called 'spiritual' acts, such as shiho-nage in aikido. And it will not do to say that,"Oh well, one slides into the other, because shiho-nage has a physical, mental, and a spiritual aspect."
My awareness of these issues has been sharpened over the past four decades, by having to teach aikido in Japanese to Japanese students who are not familiar with such distinctions, which seem deceptively clear in English.
This is may be the one most spread misconception by "westerners", to think that other cultures like Japanese think, feel and make up their universe the same way as ethnic groups who take greek logic as the source of their cultural paradigm. But even yin - yang, in - yo seem not prone to such a clear distinction or also day and night, death and life, in the same way many "westerners" would like to see it.
If we won't or can't take Ueshiba OSensei's words as advice how to do our „ internal training" as a precondition to Aikido, I doubt we will ever come near his concept, if there ever was any.
From my perspective, πάντα ῥεῖ (everything is moving and nothing remains the same) and aikido are the nearest aphorisms to each other, if anything at all is there to compare.
If we are lucky we will grow older and life will take its toll, the growing wish to get things better into perspective included. So, nothing out of the ordinary here…