Opera is a rebuke to the dogma of realism; after all, no one sings the dialogue of his life, and key moments aren’t emphasized with the roll of kettledrums or a resounding swell of orchestration. Carolyn Abbate and Roger Parker revel in the aesthetics as well as the history of an art form that seems wedded to the past yet continues to provide a grand forum for the narrative extremes, melodrama and emotional summits that can actually occur in life (but which “realism” seems unwilling or incapable of capturing). Most newer operas have a short shelf life, the authors fret, yet opera’s hold on its audience hasn’t diminished. It “can change us: physically, emotionally, intellectually.”