I have been reading Genpo Roshi’s wonderful book Beyond Sanity and Madness and yesterday I read these words:

Any teaching becomes false teaching when you get attached to it. You have to learn to move back and forth from one perspective to another without hindrance. Think of a scale: if the pointer cannot move, no matter where it points the scale is absolutely useless.

Or, relating this to music and performance: allow your awareness to move freely between rhythm in relation to the bass and percussion, harmony and pitch in relation to the other musicians, melody in relation to the rhythm, your fingering, the tactile sensation etc… don’t get stuck on a mistake and don’t get stuck on a brilliant improvisation – either way the flow of the music will be ruined. When you focus on the melody alone, you might end up behind or ahead of the rhythm, concentrate on the rhythm alone and the poetry of the melody might suffer. To concentrate on one perspective can be good for practicing, but is not good for performing.

Also see THIS and THIS.