Despite continuing debates about authorship, the work is almost always treated as Monteverdi's—although Rosand observes that some scholars attribute it to "Monteverdi" (in quotation marks). Ringer calls the opera "Monteverdi's last and arguably greatest work," a unified masterpiece of "unprecedented depth and individuality". Carter observes how Monteverdi's operas redefined the boundaries of theatrical music, and calls his contribution to 17th-century Venetian opera "remarkable by any standard". Harnoncourt reflects thus: "What is difficult to understand ... is the mental freshness with which the 74-year-old composer, two years before his death, was able to surpass his pupils in the most modern style and to set standards which were to apply to the music theatre of the succeeding centuries."