From the opening chorus of Bach's St. Matthew Passion, audiences at the Mendelssohn Club of Philadelphia performance at Girard College on Sunday will be hearing something a bit alien.
Instead of a children's chorus sailing over the top of the grand double-choir interchange, adult operatic voices among the vocal soloists will be in their place. During recitatives, the typical harpsichord won't be heard.
Who is responsible for these hard-to-explain decisions?
The chorus' namesake, Felix Mendelssohn, who rescued the St. Matthew Passion from roughly a century of obscurity in 1829 with a performance adjusted to his 19th century, as opposed to Bach's 18th.
"It's still a beautiful artistic gesture," said longtime Mendelssohn Club music director Alan Harler, who is retiring at the end of this season. "If you can change your thinking . . . and listening, we're replicating a version that was more about how people in the romantic period heard this music."
Though Mendelssohn was used to hearing Bach's Well-Tempered Clavier played among his ultra-literate family for recreational purposes, the rest of the world had changed so much that, while planning his St. Matthew Passion performance, he was told the audience would never sit through anything so long - about three hours - and complicated.
So they weren't asked to, because of changes so radical they signify a meeting of two musical minds separated by a century, something like Mozart's orchestration of Handel's Messiah.
"At some point, somebody would have rediscovered the St. Matthew Passion and performed it," said Mendelssohn scholar R. Larry Todd at Duke University. "But you had to have . . . somebody who could pull it off, musically speaking. And Mendelssohn was wired for Bach."
The famous 1829 Berlin performance, conducted by a then-20-year-old Mendelssohn, cut roughly half the piece. Harler wouldn't touch that version, opting for the 1841 Leipzig edition, which restored many cuts.
"This version is a whole and complete work of art," Harler said. "I have to believe that. Otherwise I wouldn't be doing this."
The evolution from 1829 to 1841 leaves even the brightest scholars a bit baffled. In the earlier outing, Mendelssohn used keyboard accompaniment for the recitatives - not the kind of instrument Bach would have known, but still closer than the two cellos and a bass accompanying the recitatives in 1841, when Mendelssohn presumably had a greater understanding of the piece. And though he probably could have had a children's choir in that second performance, Mendelssohn chose to stick with the 1829 Berlin approach of having the vocal soloists sing their part.
Roughly 45 minutes of the piece were still missing in 1841, and theories abound as to what guided that cutting process. Some say Mendelssohn, born Jewish but a Lutheran convert, was on the lookout for anything that smelled of anti-Semitism. A more subtle theory suggests that a more emotional experience, as opposed to the old idea of faith as an act of self-discipline, guided the cuts. In any case, the version is rather less reflective.
A longtime admirer of the St. Matthew Passion, Harler was drawn to the Mendelssohn edition because it allows the large choral forces of his 140-voice Mendelssohn Club - as opposed to the much smaller, historically accurate performances now championed by Choral Arts Philadelphia.
Only in recent years, though, were scores and parts published that made modern performances even possible - which explains why Sunday's performance is the U.S. premiere of the Mendelssohn version. To better understand Mendelssohn's journey with the piece, Harler traveled to Oxford, England, to examine his original score, urged on by his Bach advisor, Koji Otsuki, who studied with the famous Japanese Bach specialist Masaaki Suzuki. "It's really important to see what Mendelssohn thought, what he really wanted to do and, in the end, what he accomplished," he said.
Studying such documents is a highly intuitive process; what one learns from them can't always be articulated. One thing Harler observed, though, was the care taken with modifications, often delineated in the lightest of pencil marks - gray for 1829, red for 1841. Perhaps Mendelssohn knew that Bach would have to adopt outer garments that didn't entirely fit until succeeding generations became more accustomed to his works - and more curious about what they originally sounded like.
"I think Mendlssohn understood the sweep of the piece," Harler said, "even if having 140 singers makes a racket that Bach never would have heard."
The event has turned into a major opportunity for the Mendelssohn Club: The group received its largest-ever grant - $240,000 from the Pew Center for Arts & Heritage - including money for a documentary film on the subject.
Musically, Mendelssohn Club stands a good chance of making a strong case for for the edition, partly due to the group's continual artistic upswing over the past decade. Also, Sunday's performance has a lineup of soloists that would be the envy of much higher-profile organizations: soprano Susanna Phillips, mezzo-Marietta Simpson, tenor Yusuke Fujii, and, most of all, bass-baritone Eric Owens, who recently performed in a staged version of the St. Matthew Passion with the Berlin Philharmonic.
However seasoned the soloists may be, this promises to be a Bach outing unlike any other they've done. Admits Harler: "A few have expressed their dismay at certain places."