Hi j_tour,
I'm sorry for the very late reply!
No worries -- I'd forgotten entirely about this thread, although I did play this one not too long ago and remembered vaguely I'd given some advice about how I like the LH to have their own character, little phrases in their own right.
I think we're both right -- while very brisk is nice, there's not any reason it can't be done at whatever tempo sounds good.
Well, I'm officially under fire to try to figure out a good place to balance my tablet on the keys at home one of these days and show you what I was talking about, with some vocal comments while playing if I can manage it.
Well, don't hold your breath -- I'm really lazy, but you put the idea back in my head, so there's a good chance I'll get wasted and end up package-taping the tablet to the ceiling and calling it good.
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Well, that was a little too much about me ranting, but I do have just an idle question: do you find that your work on scales helped or hindered your ability to trade the motif in this Invention between hands, for the LH part? I remember it being difficult, while I could run the scales at whenever that was, to feel comfortable using the fragments of scales to carve out the motif in the LH.
Just something that popped into mind -- no right or wrong answer.

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ETA
But honestly, I (and my teacher) never considered that the going up and then down of the motif should be two separate phrases.
Oh, I see. No, that wasn't what I was trying to say -- I was just talking about the little eighth-note "accompanying" parts, in some editions even marked staccato, or slurred staccato.
I was just saying since it's only two voices one way I amuse myself is to try to play those little accompaniment chordal outlines in various ways, as though someone were singing them and trying to make a little musical joke or serious statement.
Yeah, that would probably have to be demonstrated, so that gives me further reason to make an effort at home to try to show. I'm not some master of piano, but at least I can give the idea.