The master teacher Karl Ulrich Schnabel, son of Arthur Schnabel, used to describe musical dynamics using the analogy of a stage play in which one character says to another, "I'm going to kill you!" It matters a lot where the speaker is standing in relation to the addressee, whether within arm's reach knife in hand, or half a room away.
Playing for musicians in the intimate circumstance of my home reveals repeatedly to them and to me the extent to which that distance variable is removed in our approach both to listening and to playing.
Sitting almost on top of the piano they hear things they have never heard before, even in the most familiar music.
Those are the vibrations, friends. The variability of those vibrations is my secret place in which I move as if swimming in the safest waters. Playing is not so much a matter of rendering the music as of living inside of it.
Last night I played Grieg's Poetic Tone Pictures, Op. 3. What is poetic is tone itself: Nothing sentimental, nothing "romantic" about it. I apply exactly the same principles to the tone universe of Mozart with the result, as described by a musician in the audience, that the music seems to speak.
It does speak to me; all I do is let you in on the secret of my hearing.