The sincere awe in which Brahms held Beethoven's symphonic achievements left him hesitant for twenty years or so about composing a symphony of his own, and indirectly led him to channel several of his symphonic conceptions into other musical forms. Thus, although he had begun to think about the composition of his first symphony as early as 1854, it was not completed until 1876. Something similar seems to have happened with the string quartet, a genre that Beethoven had also exalted with sixteen immortal quartets. Brahms made many failed attempts in his youth to write a string quartet, and it took many years for the first two that saw the light of day (opus 51) to achieve their final form. In contrast, Brahms wrote his sextets for two violins, two violas and two cellos (opus 18 and opus 36, respectively) both earlier and with greater ease. The second of these was written in 1864, some four years after the first.

When we think of Brahms' music, the prime elements that spring to mind are a warm, deep, full sound, intensely charged but always noble, and the wonderful balance achieved between robust ‘symphonic’ phrasing and an omnipresent sensitivity. Brahms' music combines the ‘masculine’ virtue of sturdy architecture with a "feminine" fragility, which is what makes it so truly moving. The Second Sextet is clearly endowed with both—and in spades! Despite its major tonality, it is a deeply melancholic ‘autumnal’ work with an ethereal, bittersweet atmosphere. The frequent use of polyphonic writing, especially in the slow movement and in large parts of the finale, also makes an impression on the listener. The lengthy first movement (one of the longest in Brahms' chamber repertoire) is introspective, with a largely enigmatic, mysterious narrative which remains unsettled and unsettling virtually from start to finish. In this movement’s second theme, the sequence of notes A - G - A - B - E spells out the name Aga(t)he when translated into German musical notation. This is a musical reference to Agatha von Zimbold, with whom the composer was in love and engaged for a short time (1858). The general sadness of the two middle movements is only temporarily dispelled by the scherzo’s middle section. However, the finale combines melodic passion with swift, light passages (in the style of Mendelssohn) to provide a truly optimistic conclusion.

Felix Mendelssohn lived a short but beautiful life: He grew up in a family that was both very wealthy (thanks to his banker father) and extremely cultured (his grandfather was the great philosopher Moses Mendelssohn). His prodigious and precocious musical talent found the ideal conditions to bloom since, in addition to his systematic and profound musical studies, the young Felix had an entire private string orchestra at his disposal to try out his first compositions (he would, in fact, compose twelve string symphonies for this orchestra in his childhood and early teens). In his adult life, too, he enjoyed unparalleled admiration and recognition from both the public of the time and from his peers.

Mendelssohn was sixteen when he composed his String Octet for four violins, two violas and two cellos as a birthday gift for his teacher, the virtuoso violinist Eduard Rietz (the work was completed on 15 October 1825, two days before Rietz's birthday). Although the first of Louis Spohr's Double Quartets was published that same year, Mendelssohn's Octet is considered the first true string octet in the history of music, since it wasn’t written for two quartets, but rather for eight independent instruments that coexist, intertwine and collide within a composition that is symphonic in conception. Of course, the first violin part is particularly prominent and demanding, which is only to be expected, given that it was intended for the virtuoso Rietz. However, apart from being widely viewed as the work that heralded Mendelssohn's maturity as a composer, the Octet is also considered one of his most masterful works; indeed, the composer himself reportedly said towards the end of his life that he favoured the Octet of all his works.

At sixteen, Mendelssohn was already deeply familiar with sonata form. In the Octet's dramatic first movement, he employs it with effortless flexibility, reversing the order in which the themes appear in the recapitulation and using the final coda as another opportunity to develop his thematic material in the Beethovenian manner. The slow movement is as intensely lyrical as one might expect, but never succumbs to sentimentality—in fact, the complex harmonic narrative with its constant modulations reveals an elaborate masterplan that bestows an unfettered mobility on the music, free of torrid stops and starts. The Scherzo has a connection (according to the composer's sister) to the famous “Walpurgis Night” from Goethe's Faust. The restrained dynamics, abrupt rapid gestures, staccato playing and subdued tremoli perfectly capture the wind’s breath and fairy-tale world of spirits, fairies and elves. The finale, which opens with a sweeping entrance on the second cello, ingeniously mixes elements from sonata and rondo form and employs complex, polyphonic writing at times. The result is a genuine adventurous work of undiminishing vitality and intensity.