History[edit]

In the Middle Ages, simultaneous notes a fourth apart were heard as a consonance. During

the common practice period (between about 1600 and 1900), this interval came to be heard

either as a dissonance (when appearing as a suspension requiring resolution in the voice

leading) or as a consonance (when the tonic of the chord appears in parts higher than the fifth

of the chord). In the later 19th century, during the breakdown of tonality in classical music, all

intervallic relationships were once again reassessed. Quartal harmony was developed in the

early 20th century as a result of this breakdown and reevaluation of tonality.

Precursors[edit]

The Tristan chord   Play (help·info)

The Tristan chord is made up of the notes F♮, B♮, D♯ and G♯ and is the very first chord heard

in Wagner's opera Tristan und Isolde. The bottom two notes make up an augmented fourth; the

upper two make up a perfect fourth. This layering of fourths in this context has been seen as

highly significant. The chord had been found in earlier works (Vogel 1962, 12;Nattiez 1990,[page needed]) (notably Beethoven's Piano Sonata No. 18) but Wagner's use was significant, first

because it is seen as moving away from traditional tonal harmony and even towards atonality,

and second because with this chord Wagner actually provoked the sound or structure of

musical harmony to become more predominant than its function, a notion which was soon after

to be explored by Debussy and others (Erickson 1975,[page needed]). Beethoven's use of the chord is

of short duration and it resolves in the accepted manner; whereas Wagner's use lasts much

longer and resolves in a highly unorthodox manner for the time. Despite the layering of fourths,

it is rare to find musicologists identifying this chord as "quartal harmony" or even as "proto-

quartal harmony", since Wagner's musical language is still essentially built on thirds, and even

an ordinary dominant seventh chord can be laid out as augmented fourth plus perfect fourth (F-

B-D-G). Wagner's unusual chord is really a device to draw the listener into the musical-

dramatic argument which the composer is presenting to us. However, fourths become

important later in the opera, especially in the melodic development.

At the beginning of the 20th century, fourth-based chords finally became an important element

of harmony.

The Mystic chord   Play (help·info)

Scriabin used a self-developed system of transposition using fourth-chords, like his Mystic

chord in his Piano Sonata No. 6. Scriabin wrote this chord in his sketches alongside other

quartal passages and more traditional tertian passages, often passing between systems, for

example widening the six-note quartal sonority (C – F♯ – B♭ – E – A – D) into a seven-note

chord (C – F♯ – B♭ – E – A – D – G).