Danse macabre, Op. 40, is a tone poem for orchestra, written in 1874 by the French composer Camille Saint-Saëns. It is in the key of G minor. It started out in 1872 as an art song for voice and piano with a French text by the poet Henri Cazalis, which is based on an old French superstition. In 1874, the composer expanded and reworked the piece into a tone poem, replacing the vocal line with a solo violin. According to legend, "Death" appears at midnight every year on Halloween. Death calls forth the dead from their graves to dance for him while he plays his fiddle (here represented by a solo violin). His skeletons dance for him until the rooster crows at dawn, when they must return to their graves until the next year. The piece opens with a harp playing a single note, D, twelve times (the twelve strokes of midnight) which is accompanied by soft chords from the string section. The solo violin enters playing the tritone, which was known as the diabolus in musica ("the Devil in music") during the Medieval and Baroque eras, consisting of an A and an E♭—in an example of scordatura tuning, the violinist's E string has actually been tuned down to an E♭ to create the dissonant tritone. The first theme is heard on a solo flute, followed by the second theme, a descending scale on the solo violin which is accompanied by soft chords from the string section. The first and second themes, or fragments of them, are then heard throughout the various sections of the orchestra. The piece becomes more energetic and at its midpoint, right after a contrapuntal section based on the second theme, there is a direct quote played by the woodwinds of the Dies Irae, a Gregorian chant from the Requiem that is melodically related to the work's second theme. The Dies Irae is presented unusually in a major key. After this section the piece returns to the first and second themes and climaxes with the full orchestra playing very strong dynamics. Then there is an abrupt break in the texture and the coda represents the dawn breaking (a cockerel's crow, played by the oboe) and the skeletons returning to their graves.