The modern Lydian musical scale is a rising pattern of pitches comprising three whole tones, a semitone, two more whole tones, and a final semitone. This sequence of pitches roughly describes the fifth of the eight Gregorian (church) modes, known as Mode V or the authentic mode on F, theoretically using B♮ but in practice more commonly featuring B♭ (Powers 2001). Because of the importance of the major scale in modern music, the Lydian mode is often described (or learned) as the scale that begins on the fourth scale degree of the major scale, or alternatively, as the major scale with the fourth scale degree raised half a step.
Ancient Greek Lydian
The name Lydian refers to the ancient kingdom of Lydia in Anatolia. In Greek music theory, there was a Lydian scale or "octave species" extending from parhypate hypaton to trite diezeugmenon, equivalent in the diatonic genus to the medieval and modern Ionian mode, i.e., the modern major scale: C D E F | G A B C (Barbera 1984, 233, 240). In the chromatic and enharmonic genera, the Lydian scale was equivalent to C D♭ E F G♭ A B C, and C C E F F A B C, respectively (Barker 1984–89, 2:15), where "" signifies raising the pitch by approximately a quarter tone.
Medieval Lydian mode
In the Middle Ages and Renaissance, this mode was described in two ways. The first way is the diatonic octave species from F up to F an octave above, divided at C to produce two segments: F–G–A–B–C and C–D–E–F. The second is as a mode with a final on F and an ambitus extending to F an octave higher and in which the note C was regarded as having an important melodic function. Many theorists of the period observed that B♭ is used more typically than B♮ in compositions in Lydian mode (Powers 2001).
Modern Lydian mode
The Lydian scale can be described as a major scale with the fourth scale degree raised a semitone, making it an augmented fourth above the tonic, e.g., an F-major scale with a B♮ rather than B♭. This mode's augmented fourth and the Locrian mode's diminished fifth are the only modes to have a tritone above the tonic.
Triads within Lydian mode
In Lydian mode, the tonic, dominant, and supertonic triads are all major. The subdominant is diminished. The triads built on the remaining three scale degrees are minor.
Classical (Ancient Greek)
The Paean and Prosodion to the God, familiarly known as the Second Delphic Hymn, composed in 128 BC by Athénaios Athenaíou is predominantly in the Lydian tonos, both diatonic and chromatic, with sections also in Hypolydian (Pöhlmann and West 2001, 85).
A rare, extended use of the Lydian mode in the Classical repertoire is Simon Sechter's 1822 Messe in der lydischen Tonart (Mass in the Lydian Mode) (Carver 2005, 76). A more famous example from around the same time is the third movement of Ludwig van Beethoven's String Quartet No. 15 in A minor, Op. 132 (1825), titled by the composer "Heiliger Dankgesang eines Genesenen an die Gottheit, in der lydischen Tonart" ("Holy Song of Thanksgiving by a Convalescent to the Divinity, in the Lydian Mode"). The alternating passages in F use the Lydian scale with sharp fourth scale degree exclusively. Anton Bruckner employed the sharpened fourth of the Lydian scale in his motet Os justi (1879) more strictly than Renaissance composers ever did when writing in this mode (Carver 2005, 74–75). Charles-Valentin Alkan's Allegro barbaro (Étude Op. 35, No. 5) is written strictly in F Lydian, with no B♭s present at all (Smith 2000,).
In the 20th century, composers began once again to exploit modal scales with some frequency. An example from the middle of the century is the scherzo movement of Carlos Chávez's Symphony No. 3 (1951–54). The movement opens with a fugue subject, featuring extremely wide leaps, in C Lydian with following entries in F and G Lydian (Orbón 1987, 90–91).
Pianist-composer George Russell developed a Lydian Chromatic Concept of Tonal Organization, which became highly influential in the jazz world, inspiring the works of people such as Miles Davis, John Coltrane, Ornette Coleman, and Woody Shaw (Anon. n.d.)