The "soul" is not in you, it's in the music. You don't impose your emotions on it; you allow the music to speak through you.
I know when I get the deepest emotional charge from playing music, the most passionate connection, it's always when I've managed to play it honestly and correctly, with no emotional input from me (just the desire to hear it properly).
Right.
IMO, the secret (if there is one) is in the detail. Make every note count. Great players can make very simple stuff sound amazing.
It's called "expression", of course, but that's a tricky word. I think it's about having the utmost
respect for the smallest elements of the music.
Like brushwork to a painter: if a painting lives and breathes, it's down to the attention to the brushwork. If each mark wasn't perfectly controlled, the whole thing would not work. You wouldn't say a single brush mark was "expressive" - and the painter certainly was not feeling any emotion when he put it down. But he controlled it
just so (through a combination of experience and judgement).
(And IMO the analogy works for Jackson Pollock as much as for Rembrandt
: if Rembrandt is "classical", Pollock is "jazz" - it looks splashy and uncontrolled, but constant taste and judgement is being applied; accidents are accepted if they
work. A jazz musician may often not know how what he is about to play will sound; but he plays it anyway, listens, and goes with it, maybe to somewhere else. Again, it's about giving the music enough respect, allowing it say what it seems to want to say.)