In the Romantic era, a strong connection appeared between music and literature. These instrumental pieces that told a story because of their strong literary connection are commonly referred to as program music. Common forms of program music include incidental music, tone poem, and program symphony.
Incidental music was originally intended to be played between the acts of a play. Although its primary purpose was to cover scene changes occurring on stage, incidental music reminded the audience of the action that had already happened on stage while preparing them emotionally for action that will occur in the upcoming scene. One of the most famous examples of incidental music is A Midsummer Night's Dream by Felix Mendelssohn.
Tone poems and program symphonies were both introduced by Franz Liszt. A tone poem was a single-movement composition with a strong basis in literature. Works such as Liszt's Don Quixote are obvious examples, although modern audiences may be better acquainted with The Sorcerer's Apprentice by Paul Dukas since it was the basis of Walt Disney's famous animated vignette of the same name.
Similar to the tone poem, a program symphony was a multi-movement composition with a clear literary connection. Although developed at the hands of Liszt, the program symphony found perfection in the Symphonie Fantastique of Hector Berlioz. This exciting musical journey through the horrifying drug-induced dreams of the composer found its literary basis in the program notes Berlioz composed to be distributed at the Symphony's performance. Using the idee fixe, the symphony's movements were unified into a complex and complimentary whole that continues to excite audiences today.