As a young composer in Vienna seeking to establish his reputation, Beethoven understandably concentrated most of his effort on piano sonatas and works for conventional instrumental combinations – piano trios, string quartets, violin and cello sonatas, symphonies, piano concertos. In addition, however, he experimented with a number of works for unusual combinations of instruments to enhance his income and win new friends. Altogether, between 1792 and 1801, he completed 13 compositions in this category – some were begun during his last year in Bonn and completed later while others were started in Vienna.

The Serenade, Op. 25, was probably written in 1801 and published in 1802. It must have made a favorable impression at the time because a year later an arrangement for flute and piano by another composer but corrected and approved by Beethoven was published as Op. 41.

Clearly intended to cater to the Viennese love for informal outdoor music, the Serenade consists of seven short movements, none of which demands undue concentration. The music has a charm and delicacy one does not usually associate with Beethoven – after all, this was music written to accompany outdoor eating and leisurely conversation.

Further, the flute’s graceful voice adds an unexpected note of daintiness. The first movement, for example carries the title, "Entrata." This is an Italian variant of a Spanish word "entrada," a festive or march-like prelude that was originally used for the entrance of the performing musicians in a procession. The flute prances on first all alone with a fanfare that might have been written to announce a band of fairies.

Or consider the third variation of the andante fourth movement in which the solo for the viola is accompanied by the violin’s flowing strains and the flute’s agile skipping.

In the early years of the 19^th century, piano makers introduced the sustaining or damper pedal, triggering a major breakthrough in the playing of the instrument. The pedal made it possible for the performer to sustain notes and chords, to cut them short, or to play them in a smoother legato style. Equally important, the pedal expanded the piano’s sonorities by making its full body of strings available for sympathetic resonance.

In his two piano trios of 1808, published as Opus 70, Beethoven was the first to exploit the piano’s expanded resources. In effect, these two trios did for the piano-trio literature what Beethoven’s "Eroica" did for symphonies and his three "Rasumovsky" quartets did for string quartets. Haydn, Mozart and Beethoven himself had previously written piano trios of high quality and originality, but Beethoven’s Opus 70 pair created a new standard for the expressive use of piano sonorities. The trios set the stage, in other words, for Beethoven’s monumental "Archduke" trio, completed three years later, and for the great romantic trios of Schumann, Mendelssohn and Brahms, who were particularly skillful in blending the piano’s enriched sound with those of string instruments.

Beethoven dedicated the two Opus 70 trios to a truly generous and patient friend – a Hungarian countess, Anna Marie Erdödy. The countess had married one of Beethoven’s earliest patrons, Count Peter Erdödy, in 1796 when she was only 17 years old but was now separated from her husband.

According to one account, the countess was a "very beautiful, fine little woman" and "so merry and friendly and good," but she was crippled by a partial paralysis of her legs. "Her sole entertainment was found in music," the account continues. "She plays even Beethoven’s pieces right well and limps with still swollen feet from one pianoforte to another." The countess’s disabilities and Beethoven’s growing deafness may have added to their attraction for one another.

In 1808 the countess invited Beethoven to move into her home. Beethoven had been an itinerant lodger, changing quarters frequently because of minor discomforts or disagreements with landlords, and she hoped to help him settle down. Unfortunately, the irritable and inflexible composer made a poor houseguest, and after six months of petty squabbling he moved out.

Beethoven composed the two trios while still living in the Erdödy home and dedicated them to the countess in appreciation for her hospitality. But the countess made the well-intentioned mistake of intervening in a dispute between Beethoven and his manservant, bribing the servant to keep peace with his difficult employer. This evoked a furious outburst from Beethoven, who instructed his publisher to change the dedication of the trios to Archduke Rudolph, the emperor’s younger brother and also a Beethoven student. Happily, there was a reconciliation with the countess, and Beethoven not only let the original dedication stand but subsequently dedicated to her his two great cello sonatas, Opus 102.

The trio is in three movements. The first, in sonata form, is a study in contrasts. The main theme consists of two segments – a thumping tune played by all three instruments in octave unison, and immediately thereafter a lyrical melody, dolce, in the cello. Such abrupt changes in mood and texture dominate the movement, and the two elements meet head-on in the unusually long development. The theme is further developed in the recapitulation, and the coda reverses the order of the two elements, beginning with the dolce strain and ending with the unison motive.

The trio gets its nickname "Ghost" from the slow movement, whose atmosphere of mystery, gloom and terror reminded Beethoven’s pupil, Carl Czerny of the ghost in Hamlet. Czerny may have been on to the right playwright but the wrong play. Beethoven’s sketch books reveal that, at the time of the trio’s composition, the composer was planning an opera about Macbeth and had even sketched out an opening witches’ chorus. The opera project was never realized, and whether it was related to this movement can only be conjectured.

The movement, in an agonizingly slow tempo, is based on two one-measure motives stated sotto voce at the outset. The first motive is played by the strings in the first and third measures, and the other by the piano in the second and fourth. These spectral motives are repeated ominously throughout the movement, against ghostly tremolo chords in the piano and with hair-raising climaxes.

After two such intense movements, the listener is grateful for the relaxed, happy-go-lucky finale.

Opus 135 was Beethoven’s last quartet – in fact, his last major work in any form. It was completed in October, 1826, six months before his death, at the country home of his brother Johann near the village of Gneixendorf in the Danube valley. Beethoven had taken his unstable nephew, Karl, to Gneixendorf to convalesce from a head wound that he had given himself in a suicide attempt with a pistol. The visit turned out dismally – Beethoven’s relations with Johann were strained, he detested his sister-in-law, and Karl was in constant rebellion against the restraints imposed on him.

Out of this Kafkaesque setting came a quartet of surprising warmth and intimacy. Opus 135 shares with Beethoven’s other late quartets his final preoccupation with abstract musical ideas, but here the composer is relaxing rather than plumbing emotional depths. The quartet is far shorter than the others, and except for the slow movement, the tone is conversational, even lighthearted.

The first movement is in customary sonata form, but the tempo, allegretto, is more leisurely than the usual allegro. The themes come in bits and snatches – there are at least six of them – and in the development they are geared with one another like a Swiss watch. Of particular importance is the opening phrase in the viola and its flippant answer in the first violin.

The main theme of the scherzo is marked by a disagreement over the beat to be emphasized – the first violin stresses the second beat; the second violin, the third; the viola, the first; and the cello, the first and third. The trio, longer than the scherzo proper, stimulates considerable excitement when the first violin plays a wild dance over a five-note figure insistently repeated by the other instruments no less than 51 times.

Beethoven noted a sketch of the slow movement as a "sweet song of rest or peace." It consists of a theme, only ten measures long, moving in its simplicity, and four variations. The first variation restates the theme in richer harmony. The second breaks the theme into grief-laden chords. The third repeats the theme in the minor. The fourth follows the harmonic outline of the theme but not the melody itself.

The fourth movement presents a riddle that has long teased Beethoven scholars. Beethoven super-scribed the movement "der schwer gefasste Entschluss" – roughly, "the hard-won decision." He then set forth at the top of the page two musical mottos, one a question "Muss es sein?" ("Must this be?") and the other the answer "Es muss sein!" ("This must be!"). The first motto, with the rising inflection of a question, becomes the dramatic introduction of the movement; the response motto becomes the main theme.

What was Beethoven’s meaning? One might reasonably conclude that the giant Beethoven, already ill, was facing up to his coming death. The note on the sketch of the slow movement cited above strengthens this hypothesis. But Lewis Lockwood, in his recent, highly praised biography of Beethoven, devotes four pages to the possibility of other explanations, including:

*The superscription and mottos referred to Beethoven’s difficulty in completing the quartet when he was depressed by his nephew’s suicide attempt.

*Beethoven really wanted to be working on something else. In a letter to his Paris publisher, he wrote: "It was hard going to complete this quartet because I had a much greater work on my mind. I composed it frankly because I had pledged my word and I needed the money. You can see from the motto ‘This must be’ that I wrote it with reluctance."

*The motto was the continuation of a private joke. A few months previously Beethoven had written a four-voice canon to tease a friend who, when told he must pay to have an earlier quartet performed in his home, had asked "Must this be?" The canon used the second motto and had the following lyric: "It must be. Yes, yes, yes. Out with your purse. It must be."

*Beethoven was pulling our leg. The subtitle and mottos were another example of the legalistic language Beethoven sometimes used when he wanted to be bitter or ironic, and here he was using this device simply to introduce the musical phrases that follow.

Certainly, the tone of the movement is consistent with a playful explanation. The "It must be" theme, as well as a tuneful second theme, related to that of the slow movement are treated in a carefree way. And, after a dramatic repetition of the question motto, Beethoven leaves the stage laughing.