The Requiem Mass by Giuseppe Verdi is a musical monument to art itself. It honors the great Italian writer Alessandro Manzoni, whose novel “I promessi sposi,” or “The Betrothed” in English, is among the world’s literary masterpieces.

On Friday and Saturday at the Sottile Theatre in Charleston, it will be performed by the Charleston Symphony Orchestra and Chorus, joined by the College of Charleston Concert Choir, in a special season-ending program.

Manzoni was a child of feudalism but lived through the tumultuous 19th century that saw the unification of Italy. His nationalism and use of the Tuscan dialect was instrumental in reinforcing the ideas of the “Risorgimento,” or Resurgence.

Verdi shared many of those ideas. He was a nationalist. He benefited from a unified country. He was a voice expressing popular sentiment and rallying Italians around a cause. When Manzoni died in 1873, Verdi committed himself to writing a musical setting of the Catholic funeral Mass that properly honored his role model and extended the writer’s vision of a single, unified people.

The composer, who had presented his latest opera “Aida” in 1872, was at the peak of his artistic powers and very famous. He had a little something to go on; a few years earlier, he had written a portion of a Requiem, the “Libera me” movement, in honor of fellow composer Giacomo Rossini, who died in 1868.

But that collective work never was performed, to the dismay of Verdi. Upon Manzoni’s death, Verdi revisited his “Libera me,” appending a reworked version to the end of his full Requiem. The work was premiered at San Marco in Milan on May 22, 1874, the first anniversary of Manzoni’s death.

The Sottile performances will be conducted by Maximiano Valdes, the music director of the Puerto Rico Symphony.

Soloists are soprano Jasmina Halimic, mezzo-soprano Cynthia Hanna, tenor Harold Meers and bass Adam Cioffari. Robert Taylor, director of the CSO Chorus and CSO Chamber Singers, and director of choral activities at the College of Charleston, is preparing the chorus.

The Verdi Requiem is among the most popular works in classical music, a piece that employs some of the drama one finds in opera. Its stupendous “Dies Irae” movement, with its blaring brass and full-voiced chorus, rarely fails to rattle listeners in their seats.

And the “Requiem aeternam” section of “Libera me” contains one of the most sublime passages for lyric soprano and chorus ever written.

Valdes, a native of Chile and artistic director of the Festival Casals in San Juan, said he grew up with the Verdi Requiem and closed his spring festival with the piece three weeks ago.

“I love it deeply,” he said. “There is always something to discover. The piece has meaning beyond the fact of the (religious) requiem itself.”

The Requiem alternates between panic and hope, he said. “In a sense, this is the key to the piece; it has more to do with a person dying than with God, with what can be felt and thought about in the last moments.”

This call for salvation, the anxiety conveyed in the music and the supernatural bliss expressed in its quieter movements all contrast significantly with Brahms’ Requiem, Valdes said. The latter work is more about faith and life, how to achieve peace in this world. Verdi’s masterpiece presents damnation explicitly as well as heavenly reward, Valdes noted.

“It’s very dramatic, very operatic,” he said.

Valdes, who lived and studied in Italy for many years, has a flourishing career. He conducts symphony concerts all over the world, and in recent years has become an esteemed opera conductor. He often is asked to present works from the French repertoire and has plenty of experience with the late-Romantic composers such as Mahler and Bruckner, he said.

He is especially interested in 20th-century music, including the large body of works produced by Latin American composers, which he makes a point of promoting, he said.

A few years ago, his son got a job with the Mediterranean Shipping Company and relocated to Charleston. Valdes came to visit and fell in love with the city, he said. He walked its historic streets and explored its cultural institutions, charmed by the experience.

Meanwhile, the symphony’s concertmaster and acting artistic director, Yuriy Bekker, heard about Valdes from conductor JoAnn Falletta, and from other colleagues who praised Valdes’ talent and character. (He had preceded Falletta as music director of the Buffalo Philharmonic.)

His eyes glittering from the sights of Charleston, Valdes called his agent to find out if this town had a symphony orchestra.

His agent called the symphony out of the blue one day, suggesting a meeting with Bekker. The stars had aligned. The two men got together for lunch and talked.

They soon decided on what to do, the Verdi Requiem, and how to do it, and they collaborated on selecting the four soloists, Bekker said.

When he first learned of the presence of a symphony orchestra in Charleston, Valdes was so thrilled, he did something he’s never done before, he said.

“It was the first time I asked an orchestra to hire me.”

Reach Adam Parker at 937-5902. Follow him at www.facebook.com/aparker writer.