I had the enormous good fortune as a young man to get to work with the great cellist Mstislav Rostropovich. Rostropovich, or “Slava,” as everybody called him, was the music director of the National Symphony Orchestra when I played in that ensemble, and with all his other engagements he still somehow made time to give master classes just for members of the orchestra. I learned a tremendous amount from him, and to this day I don’t seem to be able to give a master class myself without quoting Slava