How many librettos did Metastasio write?

• A. 30
• B. 60
• C. 120
• D. 10

Answer: (B)

Metastasio’s extraordinary productivity as a librettist is what this question highlights. He became the dominant voice in 18th‑century opera seria texts, supplying libretti that were quickly set to music by many of the era’s leading composers, from Hasse and Vinci to Gluck and Mozart. Over the course of his career, the body of his libretti grew large—around sixty distinct libretti is the figure most often cited in studies. This immense output is what makes sixty the best answer: it reflects both the prolific nature of his writing and the widespread, enduring use of his texts by composers across decades. While some counts differ slightly depending on whether revisions or collaborations are included, sixty is the standard benchmark that best communicates his prolific contribution to the genre.