The year Beethoven died, 1827, was also the year that his last five quartets appeared in print. They must have been lightning on the brain of the teenaged Felix Mendelssohn, who studied them avidly. Another bolt of lightning struck him at about the same time: he fell in love. History does not record any specifics about this episode, even who the girl was, but it left some significant mementos. In June Mendelssohn wrote the words and music to a song titled "Frage" (Question). It was published as Op. 9, No. 1, with a fictitious "Voss" getting credit for the words, which are:

Is it true that you always wait for me there in the leafy path by the grape arbor and ask the moonlight and the little stars about me? Is it true? What I feel can only be understood by someone who feels it with me, and who will stay forever true to me.

A few months after writing the song, Mendelssohn composed his second string quartet. The song underlies the entire quartet, as Mendelssohn emphasized when he had the published quartet include the complete song.

He wrote to a friend: "The song that I sent with the quartet is its theme. You will hear it - with its own notes - in the first and last movements, and in all four movements you will hear its emotions expressed. If it doesn't please you at first, which might happen, then play it again, and if you still find something 'minuetish,' think of your stiff and formal friend Felix with his tie and valet. I think I express the song well[.]"

So Mendelssohn wrote a quartet about being in love, and there is nothing stiff, formal, or old-fashioned about it. Young as he was, Mendelssohn had already produced a series of mature masterpieces, including the Octet and Midsummer Night's Dream Overture, but nothing in those shining works foreshadowed the stormy power of this quartet.

The transformation can be attributed to a combination of early love and late Beethoven quartets. Listeners who know those quartets will hear many echoes of them in Mendelssohn's. It begins with a gentle, reflective prologue in A major, the end of which quotes the song's opening phrase, "Ist es wahr?" (Is it true?) The long-short-long of that phrase is the basis for much of follows.

It plays a role in all four movements, though it is sometimes less obvious to the ear than it is on paper. It dominates the principal theme of the allegro that follows, which is ushered in with a dramatic touch: a flurry of sixteenth notes sets the agitated mood, then the three lower parts foreshadow the theme, much as the orchestra might introduce a big operatic aria by hinting at the theme before the diva takes it up. An even more operatic touch is the movement's final cadence, a closing formula common in opera arias since Mozart (think of the Queen of the Night's famous second-act aria in The Magic Flute). What comes between is a tightly constructed movement about yearning and conflict, driven by dissonance and intricate counterpoint.

In the second movement, like the first, a peaceful major-key prelude gives way to an unsettling contrapuntal movement - this time a fugue with a chromatic subject. It sounds very modern for 1827 and at the same time archaic and modal, like a mannerist fantasy of the 17th century (or some movements in Beethoven's late quartets). It is doubly unsettling for being rhythmically puzzling. Though the basic rhythm is in three, the fugue subject is seven beats long, and the next voice unexpectedly enters as the first one reaches the seventh beat. The prelude returns, and its strains are blended with those of the fugue, now softened into major.

The third movement is another three-part structure. It begins as a graceful, sober nocturne, but soon runs off to fairyland for one of those shimmering, darting scherzos that Mendelssohn always had up his sleeve. The nocturne returns, but the fairies and moonbeams get the last word.

The fourth movement starts with another device characteristic of opera and Beethoven's last quartets: a tempestuous recitative by the violin over tremolos in the three lower parts. The main body of the movement recalls the mood of the first movement, and literally recalls its main theme, along with the second movement's fugue, now in duple rhythm instead of triple in one more rhythmic surprise. As themes from the different movements are telescoped together, the movement subsides into the music that began the first movement, and then the quartet ends with a quotation of the second half of "Frage" - "What I feel can only be understood by someone who feels it with me, and who will stay forever true to me." Mendelssohn seems to be telling us that we've just spent half an hour listening to what love feels like to him. Rarely did he let his listeners see so much of him.

-- Lawyer and lutenist Howard Posner has also annotated programs for the Los Angeles Baroque Orchestra, the Coleman Chamber Concerts, and the Salzburg Festival.