Some time ago I did a translation (
Practice and Training to Knead the Heart/Mind) and, even more so back then than nowadays, I did not put much effort into translating a word I felt that more explanations would have over-intellectualized or done some other disservice. Just now I saw that Shibata sensei wrote something very related. If anyone read Endo sensei's article, which I linked to above, please have a look at
Shibata sensei's Thoughts on NERU essay. And check if it benefits you.