Re: Ki vs. Intent
Cool with the Chinese vocab there. Interesting to see the distinctions the Chinese thought were worth naming.
The definition for "yi" that you've given matches our use of "intent" pretty closely--not just an intention of the mind, but an intention for a particular action in a particular direction. And yet "intent" isn't just about physical actions. One of the mind tricks I use frequently is to use intent to push or lever uke with parts of my body that aren't physically touching them. E.g. they grab a wrist and I move them with the elbow of that arm, or with hara directly, neither of which is touching them. How does this match to an intent that leads movement?
Same problem with ki. Extending ki through a limb is one thing--extending ki beyond the limb is quite another. Yet the sensation of extending beyond the limb vs. not is quite different--both for nage and uke. This makes sense if you view ki as a flow through a channel--less so if you consider it to be primarily about organizing the body.