"Through the climactic scene of La Traviata the good doctor clowned, interpreted, gestured and flung his eminently quotable metaphors at us and a performance began miraculously to take shape. The problem for singers is that opera is difficult enough as music, let alone as stagecraft. Miller cajoled, joked, visibly eased tensions between contending forces, provided props, explained nuances. By the end, drama had emerged from opera. Magic, underpinned...