I know that I know a piece really well when I grasp the importance of its pushes as well as pulls, that is, the places where the note values and the articulations require me to resist forward motion, or indeed, not to move at all.
It was a true compliment when someone noted a couple of weeks ago that the Mozart I played seemed to move backwards. That is exactly what I wanted to convey. Of course, one cannot move backwards, but music is full of indications of reluctance: reluctance to move ahead, to rise, to fall, to resolve.
So much of my early Wagnerian-style training was based on a model of onward and upward that it is still hard to proceed confidently in the opposite direction.