Chromatic Fourth

In music, a chromatic fourth, or passus duriusculus, is a melody or melodic fragment spanning a perfect fourth with all or almost all chromatic intervals filled in (chromatic line). The quintessential example is in D minor with the tonic and dominant notes as boundaries, Play:

The chromatic fourth was first used in the madrigals of the 16th Century. The Latin term itself ("suffered somewhat hard") originates in Christoph Bernhard's 17th century Tractatus compositionis augmentatus (1648–49), where it appears to refer to repeated melodic motion by semitone creating consecutive semitones. The term may also relate to the pianto associated with weeping. In the Baroque, Johann Sebastian Bach used it in his choral as well as his instrumental music, in the Well-Tempered Clavier, for example (the chromatic fourth is indicated by a red bracket), Play:

In operas of the Baroque and Classical, the chromatic fourth was often used in the bass and for woeful arias, often being called a "lament bass". In the penultimate pages of the first movement of Beethoven's Ninth Symphony, the repetitions of the chromatic fourth in the cellos and basses stir up a sense of inevitable tragedy.

This doesn't mean that the chromatic fourth was always used in a sorrowful or foreboding way, or that the boundaries should always be the tonic and dominant notes. One counterexample comes from the Minuet of Wolfgang Amadeus Mozart's String Quartet in G major, K. 387 (the chromatic fourths are conveniently bracketed by the slurs and set apart with note-to-note dynamics changes), Play: