Re: Where's the hara?
I can explain what I mean regarding desire and aversion in the physical sense easily enough. When you move your body close to your partner's body and bend your arms a bit to get even closer - to get more control - you are WAY on the "desire" side. When you move or keep your body at arms length (or more) from your partner - to have more safety - you are WAY on the "aversion" side. I find I need to set things up to start with a little extra desire and then move away (or maybe I should say "expand away") so that my arms are almost 95% extended - so I can keep the center to center connection. If I were to get to 100% extended I'd be totally in "aversion" land.
I think you described the feeling of emptiness better than I could. I'm a bit dense, so please feel invited to elaborate! My limited understanding of the Heart Sutra is that it speaks to a the very sophistocated idea of how the "absolute" is *relative* to the "relative" -- *absolutely*. (Kind of like recursion!) This kind of monistic dualism or dualistic monism (however you like to think about it) is certainly the heart of the issue for going beyond the typical aikido practice of flow just enough to then crank them to the ground...
A whole lot of this is merky because of translation issues. For instance, the idea of separation and unificaiton is a little confusing in that when American's say "separation" we mean "100% cut off in all ways", and the Japanese words we are translating more have a sense of meaning "separated from the whole in some way(s), but still connected to the whole in some other way(s)". But I'm way out of my league in articulating this kind of thing.
I suppose I would sum this all up by saying that my hara is located around intestines which move somewhat freely. My physical hara is generally empty (unless I ate lunch - or I become the first male to get pregnant). Maintaining this very tangable feeling of emptiness is a good tool to help me move in an optimally connected and reflexive way. (That's what hara means to me, at my current level.)