First violinist Arnold Steinhardt is one of the founding members of the Guarneri (Gwa-NAIR-ee) String Quartet, which has been playing together for 35 years. He's written a new memoir, "Indivisible by Four: A String Quartet in Pursuit of Harmony" (Farrar Straus & Giroux). The Quartet is considered to be one of the finest string quartets performing today.