OVERTURE (Fr. ouverture, opening), in music, a detach able instrumental introduction to a dramatic or choral corn position. The notion of an overture had no existence until the 17th century. The toccata at the beginning of Monteverdi's Orfeo is a barbaric flourish of every procurable instrument, alternating with a melodious section entitled ritornello; and, in so far as this constitutes the first instrumental movement prefixed to an opera, it may be called an overture. As an art-form the overture began to exist in the works of J. B. Lully. His favourite, but not his only, form constitutes the typical French overture that became classical in the works of Bach and Handel. This French overture consists of a slow introduction in a marked "dotted rhythm" (i.e., exaggerated iambic, if the first chord is disregarded), followed by a lively movement in fugato style. The slow introduction was always repeated, and sometimes the quick movement concluded by returning to the slow tempo and material, and was also re peated (see Bach's French Overture in the Klavieriibung).
The operatic French overture was frequently followed by a series of dance tunes before the curtain rose. It thus naturally became used as the prelude to a suite (q.v.) ; and the term was then applied to the whole suite.
Bach was able to adapt the French overture to choruses, and even to the treatment of chorales. Thus the overture—move ments of his fourth orchestral suite became the first chorus of the church cantata Unser Mund sei voll Lachens; the choruses of the cantatas Preise Jerusalem den Herrn and Hochst er wiinschtes Freudenfest are in overture form ; and, in the first of the two cantatas entitled Nun komm, der Heiden Heiland, Bach has adapted the overture form to the treatment of a chorale.
Gluck could find no use for the French overture. In the epoch making preface to Alceste he laid down the rule that the overture should be the musical argument of the drama. And the perfunc tory overture to Orfeo is the only exception to the rule that in his great operas the orchestral introduction is actually inter rupted by the rise of the curtain. In 1phigenie en Tauride it is merely the calm before the storm.
The abolition of the French overture did not, however, lead at first to any widespread adoption of Gluck's loose-knit Italian texture. The next form of overture was that of a three-movement symphony (q.v.) in sonata style. In Mozart's early opera La Finta Gzardiniera the curtain rises upon what should have been the third movement ; and in all later works the overture is dis tinguished from symphonic music in style as well as form. It is a single quick movement (with or without a slow introduction) in sonata form, loose in texture, without repeats, and frequently without a development section. Sometimes, in place of develop ment, there is a melodious episode in slow time; as in Mozart's overtures to Die Entfiihrung and to the fragment Lo Sposo deluso, in both of which cases the curtain rises at a point which throws a dramatic light upon this feature. Mozart at first in tended a similar episode in the overture to Figaro, but struck it out as soon as he had begun it.
In Beethoven's hands the overture became more and more unlike the symphony, but it no longer remained an inferior species ; and the final version of the overture to Leonora is the most gigantic single orchestral movement ever based on the sonata style. Weber's overtures work out prominent themes in his operas in a loose but effective sonata form, and are effective concert-pieces besides serving Gluck's purposes admirably. On the overture to Mendelssohn's Elijah, see MENDELSSOHN.
Overtures to plays naturally tend to become detached from their surroundings; and hence arises the concert overture, led by Beethoven's mighty Coriolan, and second only to the symphony as an orchestral art-form. Its derivation implies that it is pro gramme-music (q.v.), but the programme need not impair the form, whether the form be Berlioz's or Brahms's, and the pro gramme particular or generalized. Among overtures with a gen eralized programme Mendelssohn's Hebrides overture is a perfect masterpiece; and so is Brahms's Tragic overture, one of the greatest orchestral movements since Beethoven. Brahms's Aca demic Festival Overture is a glorious working out of German student songs.