The New Student's Reference Work/Quartet

Quartet', a piece of music arranged for four solo voices or instruments, in which all the parts are obligato — that is, no one can be omitted without injuring the proper effect of the composition. A mere interchange of melody, by which the parts become in turn principal and subordinate, without the interweaving of them, does not constitute a quartet. Quartets for stringed instruments are generally arranged for two violins, a viola and a violoncello, and are sonata in form — that is, have a progression of thought and movement. They originated with Haydn, and were further developed by Mozart and, notably, by Beethoven, who perfected the art of part-writing in music. Subsequent writers are Schubert, Spohr, Mendelssohn, Schumann and Brahms. Vocal quartets were a frequent feature in oratorios and operas up to the time of Wagner.