A quartet and the lore of a lovestruck Mendelssohn

Felix Mendelssohn intended to dedicate his String Quartet (Op. 12) to one of his sisters’ closest friends.Hulton Archive/Getty Images

On Sunday, the Parker Quartet performs Felix Mendelssohn’s String Quartet (Op. 12) in Harvard University’s Paine Hall. Composed in 1829, the quartet has acquired a bit of romantic lore: Mendelssohn intended to dedicate it to Betty Pistor, an amateur singer and one of his sisters’ closest friends, but, after finishing it, learned that Betty was engaged to Adolph Rudorff, a Berlin lawyer. Mendelssohn seemed to laugh it off — joking that, fortunately, it would only require a pen-stroke to change the dedication from “B.P.” to “B.R.” — but tales of young, lovestruck composers inevitably gain traction.

In fact, the Mendelssohns and the Pistors had a multifaceted relationship. Carl Pistor, Betty’s father, the sort of well-off Berliner who epitomized the Mendelssohns’ social circle, manufactured precision scientific instruments — a craft he learned, in part, from Felix’s uncle, Nathan Mendelssohn. Pistor was also a music lover who, in 1827, purchased a large cache of Johann Sebastian Bach’s manuscripts. Felix, already devoted to Bach’s music, beat a path to Pistor’s door, offering to sort the collection. Meanwhile, Betty became a regular at musical evenings at the Mendelssohn house.

But Betty and Felix’s friendship repeatedly stumbled over misapprehensions — of all kinds. According to a family memoir by Betty’s son Ernst, at one point, Felix visited the Pistor house and was greeted by the sound of Betty and a friend laughing, which the sensitive composer assumed to be directed at himself. His sisters tried to make amends by inviting Betty to Felix’s birthday party. Carl Pistor objected on grounds, he insisted, of propriety; but the Mendelssohns, converted and assimilated Jews, suspected anti-Semitism. (Other branches of the Pistor family were, after all, prejudiced.) This time, Betty smoothed things over.

Ironically, perhaps, a crucial backdrop to the friendship was a celebration of a monument of German Christianity: the 1829 revival, under Mendelssohn’s direction, of Bach’s “St. Matthew Passion,” a signal event in establishing Bach’s modern reputation. Betty was a fixture in rehearsals and sang in the performances. The shared experience, just maybe, made it into the Op. 12 quartet. Its finale is in 12/8 time — four beats to the bar, each beat divided into three eighth notes — a steady, swirling tread that Mendelssohn, despite his love of triple time, had apparently never tried, but one that distinctly, dramatically marks the “St. Matthew Passion.”

Betty, who assumed Felix’s offer of a dedication was a joke, only learned many years after his death that the quartet had, indeed, been written for her. One final irony: when Ernst Rudorff’s memoirs were first published, in 1938, all references to the Mendelssohns were scrubbed, due to Nazi censorship. Even the future, it seems, conspired against the couple.

The Parker Quartet performs Felix Mendelssohn, Sivan Cohen Elias, and Dmitri Shostakovich Feb. 26, 3 p.m., at Paine Hall, Harvard University. Free; tickets required. 617-496-2222; www.ofa.fas.harvard.edu/boxoffice

Matthew Guerrieri