The crux of the matter?

At my piano lesson today, after we had worked for a while on the Brahms Rhapsody in B minor (Op. 79 No. 1), which I've been slogging away at for months now, my teacher said (paraphrasing a bit, but this was the gist of it), "The problem is that you don't know what you want to do with this. It's not technical ... You're just letting whatever happens happen." And he was mostly right (as usual). We have talked about things like imagining the piece orchestrated (which instrument would play which line, etc.), which somewhat helps, but when I sit down at the piano all of that flies right out of my head and there I am, thinking only of what notes I have to play.

But exactly how loud or soft do I want those notes to be? How articulated and phrased? What mood do I want to evoke, even if just in myself?

It is obvious that if you have a really clear idea of how you want something to sound, it is much more likely to come out that way. I think this is why sometimes technically difficult pieces are easier to convey -- you have no choice but to think hard about what the end result should be and how to get there. It's the easier pieces that often harder to pin down, perhaps because there are so many more options.

The Schumann cello concerto, though admittedly difficult enough technically is also difficult in this way, too. I'm afraid I'm not too clear on the answers to these questions with regard to this piece, either. This is the scary part about it.

Yet I balk at making decisions. I'm not sure why this is. I keep playing and practicing it, hoping it will all become clear to me, even though I know it should be the other way around (i.e., clarify mentally and then play and practice to achieve that result).

So big sigh ... but I will keep at it.