Consider for a moment that every note of music heard in this concert reflects a specific decision made by the composer, Mahler or Fauré or Brahms, sitting at piano or writing desk, or perhaps out for a long stroll, turning over the many options running through his head. Which instrument will he feature at a particular point in the piece? How about the other instruments? Will they simply provide an accompaniment, engage in antiphonal dialogue, rest for a few beats, join together in unison? And, of course, the composer is making such decisions on top of the fundamental work of crafting melody, harmony, rhythm, etc. Picture Brahms, for example, laying out the first measures of what would become the Op. 25 piano quartet. To which of the four instruments will he assign the lovely opening tune? Brahms settles on the piano alone, softly playing in octaves. Simple rhythm, no chords until the end of the phrase. The strings wait. The piano’s descent through the first four bars leads naturally to the low D that begins the next phrase. Now the cello makes its first entrance, joining the piano to offer the same tune in a new key, almost heartbreaking in its change of color. Two bars later the viola picks up the tune, then the violin, and the instruments softly cadence together in preparation for the next theme.

Look at the opening of Fauré’s quartet. Like Brahms, he plunges directly into his first melodic theme, but here it is played by strings together, violin and viola in unison, cello doubling them an octave lower. There’s a noble, orchestral quality to the massed sound of the three instruments in perfect synchrony. The piano accompanies them with offbeat chords. Everyone plays forte. After the brief opening phrase, there’s a sudden shift to pianissimo, but with no loss of momentum. The piano now adds rippling figuration to its chords and soon introduces a melody of its own, providing a counterpoint to the string trio as it continues with its opening theme. Mahler’s quartet, in contrast, starts with a repetitive accompaniment figure in the right hand of the piano. Only after that is established does the first theme appear, in this case played in the bass by the pianist’s left hand, the string trio still waiting.

In the piano quartet genre, the piano often plays an outsized role in the ensemble. Even when not the focus of attention, it is a vital element of the overall sound. In loud passages, it can add the same kind of reinforcement that brass and percussion bring to an orchestral tutti. When the music is soft, its filigrees of arpeggios can make things sparkle. In its expressiveness and ability to sing, the piano is a worthy match for violin, viola, and cello, such that any composer writing for piano quartet wants to make the most of the magical changes of voice that result when bowed strings and hammered strings converse with one another.

Mahler’s Piano Quartet in A minor is an anomaly, the only piece of chamber music from a composer whose output otherwise consisted purely of symphonies or songs for solo singer with piano or orchestra. He was sixteen years old when he wrote the quartet. It is one movement long, brooding and passionate. The opening three-note motif echoes the Prelude to Wagner’s seminal Tristan und Isolde—a leap upwards from the first note to the second, followed by a half-step fall. It permeates the quartet, while also foreshadowing what would be its frequent reappearances in Mahler’s later scores. One is tempted to acknowledge its importance with the German term Urmotiv, a primal motif or original source from which will flow worlds—three notes that encapsulate the un-nameable longings of the Romantic soul.

The opening of Fauré’s C minor Quartet is also serious in tone, but more full-voiced and self-assured, sounding more like a statement than a question. Its lighthearted second theme, in a major key, jumps from viola to violin to cello, then is picked up by the piano. Such games of musical tag recur throughout the movement. The second movement scherzo is even more playful, beginning pizzicato, leading to very fast figures in the piano with skittish triplets. The phrases of its theme are six bars long, a very unusual feature (coincidentally, also a feature in the last movement of the Brahms). The tender third movement, marked adagio, begins with simple chords in the piano that introduce a short rising line in the cello. The cello repeats its line higher, now joined by viola, then, on its third iteration, higher still, with the further addition of violin. At this point the three instruments are playing in unison, not separated by octaves, a rich organ-type sound that Fauré loved. The last movement is played at a furious tempo, at least as fast as the scherzo, with urgent rising scales and shifting harmonies, modulating quickly from minor to major, encapsulating in a few bars the tendency of the entire movement towards major. The harmonies throughout include surprising dissonances and unexpected juxtapositions along with sudden changes of mood, giving hints of the new directions that were on their way in the music of Fauré’s younger compatriots Debussy and Ravel.

Brahms’s G minor Quartet is built on a similar four-movement structure as the Fauré, but one-third longer in duration. The somber opening bars, described above, lead briefly to a sweet echoing theme in the treble, but then we are pulled back into a transformed version of the first theme, now loud, filling the entire musical space, energized with sixteenth-note interjections in octaves. Suddenly it is quiet again, piano and strings whispering to one another. Similar contrasts continue to play out over the course of this drama, the individual musical characters gradually revealing more of themselves through expressions of sadness or serenity, anger or tenderness, showiness or cooperation. As the Intermezzo begins, we get a brief respite from the piano. Over rapidly repeated triplets in the cello, quiet but agitated, the violin and viola spin out an anxious duet. When the piano softly enters, the driving triplets continue, suggesting an underlying narrative fraught with emotion. We could almost be listening to one of Schubert’s songs. Perhaps it’s no coincidence that the triplets call to mind the pounding hoofbeat rhythm in his “Elfking.”

The third movement welcomes us into the warmth and conviviality of E-flat major, as if at a social gathering in a Viennese parlor or pub. Violin and cello sing a folksong together, accompanied by piano and viola. The onlookers cannot resist joining in. A marching rhythm is introduced. Violin and viola imitate the sound of distant trumpets. A door is flung open, and here are the marchers, glorious in their finery. Perhaps they are a gypsy band, instruments in hand, ready to launch into the quartet’s last movement, a “Rondo alla zingarese,” or “rondo in gypsy style.” It is essentially a collection of high-energy dances, each quite self-contained, very much in the spirit of Brahms’s famous Hungarian Dances. In the middle of the movement, the band takes a break from the uproar to play a rapturous love song, pulling their bows deep into the glowing souls of their fiddles. Then it is back to the dance, the musicians showing off a bit more before their headlong race to the final bar.