Composed in just three weeks, this sextet in one movement is considered Arnold Schoenberg’s earliest important work. It was inspired by Richard Dehmel’s poem of the same name, combined with the influence of Schoenberg's strong feelings upon meeting Mathilde von Zemlinsky, whom he would later marry. The movement can be divided into five distinct sections which refer to the five stanzas of Dehmel's poem.

Dehmel’s poem describes a man and woman walking through a dark forest on a moonlit night. The woman shares a dark secret with her new lover: she bears the child of another man. The stages of Dehmel 's poem are reflected throughout the composition, beginning with the sadness of the woman's confession, a neutral interlude wherein the man reflects upon the confession, and a finale reflecting the man's bright acceptance (and forgiveness) of the woman. Verklärte Nacht was controversial at its 1902 premiere. A particular point of controversy was the use of a single 'nonexistent' (that is, uncategorized and therefore unpermitted) inverted ninth chord, which resulted in its rejection by the Vienna Music Society. Schoenberg remarked "and thus (the work) cannot be performed since one cannot perform that which does not exist".

The Sextet in D major is among those pieces published with high opus numbers many years after Mendelssohn's death. It was actually written in May 1824, when the composer was 15 years of age. No composer's lifetime performances for this work are documented.

It is scored, unusually, for a single violin, two violas, cello, double bass and piano, instrumentation that provides its own rich sonorities. The scoring, tipping the balance of the strings toward the darker and lower registers, gives the piano a dominating position in most of the piece. This makes the Sextet more of a chamber piano concerto than a pure chamber piece.

The composer's autograph of the score (in his Nachlass at the Berlin State Library) has a date at the end of it: May 10, 1824. The manuscript is relatively clean and contains too few corrections to let us track the evolution of the work. It is also never mentioned in Mendelssohn's letters.