Definition
The church modes are the diatonic scales on which Gregorian chant and Renaissance polyphony are based. A mode is not just a succession of whole tones and semitones: it is defined by a finalis (the note on which the melody concludes), an ambitus (the typical range of the melody) and a reciting tone (also called tenor or modal dominant), the note on which the chant insists. In Fux's counterpoint the modes are the basis of every exercise.
The four finals and the eight modes
Medieval theory recognizes four finals, each with an authentic mode (ambitus from the finalis to the octave above) and a plagal mode (prefix hypo-, ambitus from a fourth below to a fifth above the finalis).
| Mode | Name | Finalis | Ambitus | Reciting tone |
|---|---|---|---|---|
| 1 | Dorian | D | D–D | A |
| 2 | Hypodorian | D | A–A | F |
| 3 | Phrygian | E | E–E | C |
| 4 | Hypophrygian | E | B–B | A |
| 5 | Lydian | F | F–F | C |
| 6 | Hypolydian | F | C–C | A |
| 7 | Mixolydian | G | G–G | D |
| 8 | Hypomixolydian | G | D–D | C |
Rule of thumb: in the authentic modes the reciting tone is a fifth above the finalis, but in Phrygian the fifth B becomes C; in the plagal modes it is found a third below that of the corresponding authentic mode, with B becoming C in Hypomixolydian.
The twelve-mode system
In 1547 Glarean (Dodecachordon) added the modes on A (Aeolian and Hypoaeolian) and on C (Ionian and Hypoionian), recognizing a practice already widespread. Zarlino, in the Dimostrationi harmoniche (1571), renumbered the modes starting from C. The mode on B (Locrian) remains theoretical because its fifth B–F is diminished.
Fux's six modes
Fux works on the six modes with finals D, E, F, G, A, C (Dorian, Phrygian, Lydian, Mixolydian, Aeolian, Ionian) and excludes B. For each he writes a cantus firmus: in D Dorian D F E D G F A G F E D, in E Phrygian E C D C A A G E F E. Fux does not distinguish the exercises as authentic and plagal: what counts is the finalis, and the ambitus of the melody depends on the voice in which it is placed.
Division of the octave
Each authentic mode divides into a species of fifth plus a species of fourth: Dorian is D–A (fifth) + A–D (fourth). The plagal uses the same two species in reverse order: A–D + D–A. This division is the key to the modal answer in the fugue: what the subject presents in the fifth, the answer presents in the fourth.
How to recognize a mode in a melody
- Look at the final note and the internal cadences.
- Check the range: from finalis to finalis (authentic) or from a fourth below to a fifth above (plagal).
- Look for the note the melody insists on and the characteristic leaps (in Dorian D–A, in Phrygian E–C).
- Observe the position of the semitones relative to the finalis: in Phrygian the semitone is above the finalis (E–F), in Lydian below the fourth (the fourth F–B is augmented, and Bb is often used).
Typical mistakes
- Confusing the church mode with the modern mode of the major scale: the old concept includes finalis, ambitus and melodic formulas, not only the order of the intervals.
- Considering Hypodorian and Aeolian the same thing: they have similar ambitus (A–A) but different finals (D and A).
- Forgetting musica ficta: in practice Lydian often uses Bb, and Dorian raises C at the cadence.
Modern application
- Film scores: Dorian and Mixolydian give an archaic color without sounding sad or triumphant; many epic themes use a plagal melody that revolves around the finalis instead of rising to the octave.
- Pop: thinking in terms of finalis and reciting tone helps you write hooks that insist on one note (the reciting tone) and close on another (the finalis).
- Choirs: a Gregorian chant harmonized with a drone on the finalis and the reciting tone is an effective opening for a cinematic choir.
Related topics
Dorian mode, Phrygian mode, cantus firmus, musica ficta, modal clausulae and cadences, fugue in the modes.