On her new album, opera star Cecilia Bartoli tackles the work of Baroque composer Agostino Steffani.

TERRY GROSS, HOST:

Agostino Steffani. Never heard of him? You're not alone. He was a Baroque composer, priest, and diplomat whose music has, until recently, been almost completely forgotten. A production last year and a new recording have convinced classical music critic Lloyd Schwartz that Steffani's continued neglect would be a big mistake.

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LLOYD SCHWARTZ, BYLINE: I never heard of the Baroque composer Agostino Steffani until last year when the Boston Early Music Festival presented the North American premiere of Steffani's "Niobe," an opera about the mythical queen who bragged so much about her many children, the gods killed them all in revenge.

One of the leading roles, Niobe's husband, King Anfione, was played by the early music superstar, countertenor Philippe Jaroussky, who sang the opera's most sublime aria, a hymn to the harmony of the spheres. I couldn't wait to hear Jaroussky again and was eager to hear more Steffani. Now I have my wish.

The celebrated coloratura mezzo-soprano Cecilia Bartoli has been studying Steffani and he's the focus of her latest CD, "Mission." This album includes many arias and duets - Steffani was especially admired for composing duets - that have never previously been recorded. And on several cuts Bartoli is joined by the phenomenal Philippe Jaroussky.

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SCHWARTZ: Bartoli has an astonishing capacity for both vocal fireworks rare for a mezzo-soprano and warm delicate lyricism. And they alternate in a startling way on this new recording. She gets to sing the same aria from "Niobe" that blew me away when Jaroussky sang it in Boston.

She's playing a king who is something of a philosopher and would rather contemplate the music of the spheres than rule his country.

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SCHWARTZ: "Niobe," like many of Steffani's operas, has political overtones and on one level it's a cautionary tale about the obligations of a leader. One reason for Steffani's neglect may be the active life he led outside of music. As a boy soprano, his talent brought him in contact with powerful political and church leaders. He was an Italian who spent most of his professional life in Germany, where he even met and encouraged the younger George Frideric Handel.

As a bishop and diplomat, his high position meant that he had to use someone else's name on some of his music. But now, with the powerful advocacy of Bartoli and Jaroussky, I'm sure we'll be hearing a lot more Steffani.

GROSS: Lloyd Schwartz is classical music editor of the Phoenix and teaches in the creative writing program at the University of Massachusetts Boston. He reviewed "Mission," a new recording by Cecilia Bartoli on the Decca label. Transcript provided by NPR, Copyright NPR.