I suspect that many of the readers of this book will, like me, have been occasionally discomfited by an innocent and entirely reasonable question from someone just beginning to explore classical music. I have sometimes been asked to define the word ‘symphony’ by people expecting a straightforward and definite answer – the sort of answer one might receive upon asking a mechanic what a spanner is. It is always a shame to disappoint such enquiries, but the fluid nature of musical composition means that a concise and accurate answer is virtually impossible. The etymological root of the word ‘symphony’ is very little help: it is originally Greek and simply means ‘voices sounding together’. This definition would exclude compositions for solo monophonic instruments, where there is no possibility that any notes will ‘sound together’, but very little else. Indeed, symphonies have been written for all manner of forces. Shostakovich’s Leningrad Symphony, for instance, employs a very large orchestra with no fewer than 21 brass players, whereas Schoenberg’s Chamber Symphony No. 1 requires only fifteen players. Symphonies have even been written for a single player at an organ console. The symphony has occasionally embraced soloistic elements: Berlioz’s symphony Harold in Italy calls for a solo viola, and one of Britten’s late works is a Cello Symphony. Voices have been added to the orchestra many times, ranging from the brief wordless contributions of soprano and baritone soloists in Nielsen’s Sinfonia espansiva to the massed choirs of Havergal Brian’s Gothic Symphony. Mahler’s Das Lied von der Erde, which the composer subtitled ‘a symphony for alto and tenor soli and large orchestra’ is effectively an orchestral song-cycle, as is Shostakovichs’s Fourteenth Symphony, scored for soprano and bass with the accompaniment of strings and percussion.

A similar variety can be found in the physical constitution of the symphony. The number of movements is usually thought of as four, though even Mozart wrote several three-movement symphonies, of which the most famous are Nos. 31 (‘Paris’) and 38 (‘Prague’). Beethoven added a fifth movement in his ‘Pastoral’ Symphony, and Messiaen included as many as ten movements in his massive Turangalîla Symphony.