Anselm Hüttenbrenner, one of Schubert’s regular drinking partners, loved to tell the story of the night he invited the composer over to share some bottles of Szekszárd, a Hungarian red wine he had received as a gift. They drained the wine to the last drop, he said, and then Schubert sat down and composed the wonderfully lovely song, Die Forelle [“The Trout”], from which this famous piano quintet takes its name. Schubert even dated the manuscript “at 12 o’clock at night,” to pinpoint the moment that yet another song poured forth as freely as wine. That was on Feb. 11, 1818. In fact, Schubert had composed Die Forelle early in 1817; he was merely writing it out from memory for his dear friend that night a year later, under the beneficial influence of the blood-red Kadarka grape, and he was probably far too giddy to worry about fraud. For many years, Schubert’s reputation rested on such anecdotes, which created an abiding image of him as a good sport who composed music quickly and without effort. Hüttenbrenner apparently was not even suspicious when Schubert appeared to compose Die Forelle off the top of his head, without once stopping to change a note, in handwriting as clean and legible as possible after several bottles of Szekszárd.

It has taken musicians some time to recognize that Schubert’s beguiling natural voice was the result of serious study, hard work, vision and the kind of inner struggle we associate with his Viennese contemporary, Beethoven. Even Robert Schumann, who understood the true depth of Schubert’s genius better than anyone else at the time, once described him as a “guileless child romping among giants.” Both the song Die Forelle, which reveals Schubert’s most playful side, and the great piano quintet, which treats the Forelle theme to a magnificent set of variations, have only perpetuated this image over the decades, for these two have long been among Schubert’s most popular works.

Mitsuko Uchida and CSO musicians perform The Trout Quintet on March 13-18 at Symphony Center.

The song itself, a setting of a commonplace poem by Christian Friedrich Daniel Schubart, is one of Schubert’s most felicitous creations. It was probably composed early in 1817 — Schubert was just 20 years old — although the exact timing can’t be determined because the first draft is lost. The years 1815 to 1817 are the heyday of Schubert’s songwriting; more than 300 songs can be dated to that three-year outpouring alone, and 1817, although responsible for fewer works than the previous two years, produced some of his greatest songs, including An die Musik and Der Tod und Das Mädchen [“Death and the Maiden”]. Die Forelle, a delightful song in three stanzas, with the third unexpectedly different from the first two, quickly became a favorite, and to meet the unusual demand, Schubert made several copies of the song, each time changing details ever so slightly. (He fussed in particular with how it begins and ends; the familiar opening piano figuration as we know it appears in only one version.) This was one of his best-loved songs almost from the start, and it remains so today.

Die Forelle, however, went on to even greater popularity once it became the anchor of a new piece of chamber music composed two years later. Schubert and his friend Josef Vogl spent the summer of 1819 in the town of Steyr, nestled in the “inconceivably lovely” countryside some 90 miles west of Vienna. There they met Sylvester Paumgartner, a rich merchant and enthusiastic cellist with more money than talent. His large home included a well-stocked music library, a music room on the first floor, and a grand performing salon upstairs. He told Schubert that he loved Die Forelle and commissioned him to write a chamber work that incorporated a set of variations on the tune.

As a model, Paumgartner suggested a rather lifeless piano quintet in E-flat by Johann Nepomuk Hummel (taught by Mozart and admired by Chopin), which had a relatively undemanding cello part that Paumgartner was pleased to have mastered. He even dictated that Schubert write for the same five instruments as Hummel — piano, violin, viola, cello and— instead of a second violin, which would later become the standard choice — a double bass.

Like much of Schubert’s most enduring music, the Trout Quintet was not written for the concert hall, but for musicians who wanted something to play at home. Schubert did not finish the quintet that summer in Steyr, no doubt disappointing Paumgartner’s dream of introducing it in his own second-floor salon. The score was apparently finished sometime that autumn, after Schubert returned to Vienna. But as with many basic facts about the life of Schubert, who was never a boldfaced name even at the height of his powers, we don’t know for certain. There is not a single account of the first time five performers shared the immeasurable joy of playing this infectious piece for a roomful of music lovers. Even Schubert’s manuscript is lost; a set of parts is the only surviving primary source.

Note: Mitsuko Uchida will sign CDs in the Grainger Ballroom after the March 14 matinee.

Die Forelle is the basis for just a single movement of the quintet, yet the naturalness of its lyrical effusion and the pictorial quality of the accompanying figures — as well as the sheer joy it communicates about the very process of making music — has infected the entire composition. The Trout Quintet represents Schubert at his most natural, unaffected and carefree. In fact, this is truly music of Schubert’s innocence, before he contracted syphilis, probably late in 1822, and began to see life, and therefore music, in a darker and more complex light.

Schubert writes not four movements, as convention — and Hummel’s model — dictate, but five: an exploratory sonata-form movement, a songlike andante, a dazzling scherzo, and the requested set of variations on Die Forelle slipped in just before the rollicking finale. Schubert used to be faulted for writing sonata-form movements that were so different from those by Mozart or Beethoven — Schubert’s start developing things before the so-called development section and play fast and loose with the common key scheme. In time, he has been more rightly understood as one of the earliest and boldest of the great romantic innovators, breaking with classical procedures again and again in favor of brazen harmonic license and freedom of form.

Not one of Schubert’s five movements is quite textbook standard, because Schubert was working with harmonic colors he loved — the very opening of the first movement slips unconventionally from A major to F major and back again — and developing long forms built as much on the narrative power of extended melody as on classical harmonic tension. Schubert is one of music’s greatest storytellers, and melody is his voice — unforgettable and innately compelling, drawing us in and leading us on, in a way known to few composers.

In the fourth-movement set of variations on “Die Forelle,” Schubert dissects his little song and finds in it a world of ideas to investigate. With his born sense of development — not in the strict classical meaning, but as a freewheeling process of exploration and invention — he manages to make great things of even the tiniest detail, such as the piano’s bubbling arpeggios, originally written to depict the darting fish and the sparkling waters in the poem by Schubart, whose name would soon no longer be confused with Schubert’s.

Phillip Huscher is the program annotator for the Chicago Symphony Orchestra.

TOP: An illustration of Schubert at the piano, surrounded by a small audience.