Walter Levin escaped the Nazis as a child and went on to spend 40 years as founder and first violinist of the La Salle Quartet – and longer as a feared teacher. (He once kicked James Levine out for being unprepared.) At age 91, dependent on his near-superhuman wife, and barely verbal, music is his one remaining tether to the wider world. And when giving a lesson to a young quartet, we can see his faculties gradually revive. (includes video)