Early in their fascinating, sometimes maddening cornucopia of erudition, The New Music Theater, Eric Salzman and Thomas Desi define their subject: “Music theater can be considered the confluence or adding up of language-like expressions: verbal or spoken language (the story; the libretto), physical movement or body language (gesture, dance), images or visual language (décor or design), and sound or musical language (pitch and rhythm; vocal and instrumental).” The book’s subtitle, Seeing the Voice, Hearing the Body, aptly conveys the nature of this porous and flexible art form, in which disciplines