What is a symphony?

The word also names an ensemble, which is where most of the confusion starts. A symphony orchestra is the body of about 80 to 100 players that exists to play symphonies. A symphony is the thing it plays.

The standard four-movement plan

The standard four-movement plan settled during the second half of the eighteenth century and remained the default for well over a century after that. Each movement had a recognised function, and an audience of the period knew what was coming in the same way a reader knows the shape of a chapter.

Two things in that table matter. The first movement carries the structural argument. The third movement is the one that changed name: Haydn and Mozart wrote a minuet, and Beethoven turned it into a scherzo, faster and harder, and the minuet did not come back.

The major exceptions, which are numerous

The exceptions arrived almost as soon as the plan did. Beethoven's Sixth Symphony has five movements and the last three run without a break. Berlioz wrote five for the Symphonie fantastique in 1830 and gave the piece a written programme. Sibelius compressed his Seventh into a single continuous movement. Mahler put a contralto into the Third, a soprano into the Fourth and a chorus into the Second, nicknamed the Resurrection, and his Eighth is in two enormous parts and acquired the nickname Symphony of a Thousand from the forces it requires.

Length varies as widely as shape. Rachmaninov's Second Symphony of 1907 is in four movements and runs about an hour uncut, though for decades it was played only in heavy cuts. Elgar's Cello Concerto of 1919 is also in four movements and lasts about 30 minutes, so the number of movements says nothing at all about scale.

Some of the largest orchestral works are not symphonies. Elgar's Enigma Variations of 1899 is fourteen variations on an original theme, the ninth of them being Nimrod, and it is a full-length orchestral piece with no symphonic pretensions whatever. Holst's The Planets, written between 1914 and 1917, has seven movements running about 50 minutes, no Earth and no Pluto, and a wordless offstage female chorus in Neptune, and Holst called it a suite.

How the symphony grew, from Haydn to Mahler

The symphony grew, in about 150 years, from house music to a public monument. Joseph Haydn wrote 104 symphonies, most of them for the Esterhazy court orchestra of about 25 players, where he spent nearly thirty years; but No. 1 predates that appointment of 1761, and the last twelve, Nos. 93 to 104, were written between 1791 and 1795 for Johann Peter Salomon's much larger London orchestra after Prince Nikolaus died in 1790. Most of them last twenty minutes or so, and in writing them he fixed the four-movement plan for everybody who came after. Beethoven wrote nine and made each one an event: the Third broke the length convention, the Fifth added trombones, piccolo and contrabassoon in its finale, and the Ninth brought in soloists and chorus and ended the assumption that a symphony was purely instrumental.

After Beethoven the difficulty was the number nine itself, and several composers wrote in its shadow. Mahler left nine numbered symphonies, an unfinished Tenth and Das Lied von der Erde, a symphony in all but title that he declined to number. By his time the orchestra had reached the size it still is, and the symphony had absorbed folk song, military bands, church music and the human voice.

The twentieth century, and the cycles that resulted

The twentieth century did not abandon the symphony; it multiplied it. Ralph Vaughan Williams completed nine, beginning with A Sea Symphony, which uses a chorus throughout, and finishing in his eighties. In Wales, Daniel Jones wrote thirteen symphonies and Alun Hoddinott ten, while William Mathias wrote three alongside the church and organ music he is better known for. Alfred Schnittke, working in the Soviet Union, wrote symphonies that quote and collage many idioms at once, a method he called polystylism, and one of them, the Symphony No. 0, waited decades for its first performance.

The most systematically worked-out cycle of the period came from Denmark. Vagn Holmboe, who lived from 1909 to 1996, built symphonies by what he called metamorphosis technique, growing an entire movement out of one small cell of material so that the argument never repeats itself and never breaks. He wrote thirteen numbered symphonies and an unnumbered Sinfonia in Memoriam, Op. 65.

Why the form has lasted

Recorded complete cycles are how most listeners now meet a symphonist's whole output. The complete Holmboe symphonies were recorded by Owain Arwel Hughes with the Aarhus Symphony Orchestra for BIS between June 1992 and January 1996 and issued as a boxed set in 1996, in the composer's lifetime; Holmboe wrote the Sinfonia in Memoriam at Hughes's request, and Hughes gave its premiere. Hughes also recorded a Rachmaninov cycle for the same label.

The symphony has outlasted the court that paid for it, the aristocracy that subscribed to it and the certainty that it would be in four movements. What has kept it alive is the thing in the definition: a symphony is an argument long enough to change its own mind, played by the largest instrument anybody has ever built.

Also in this programme

• The orchestraHow a symphony orchestra is put together
• Orchestral instrumentsThe instruments of the orchestra, family by family
• The sections of an orchestraThe four sections of an orchestra, and what each one is for
• Alfred SchnittkeNagasaki, Symphony No. 0 and a premiere fifty years late