The church modes (or Gregorian modes) are the system of eight scales that organized the sacred music of the Middle Ages. They are the basis of Gregorian chant. Each mode is defined by its final (finalis, the note of rest) and its range, and the modes are grouped in authentic–plagal pairs.
What are the church modes?
Before the tonal system of major and minor, Western music was organized in modes. Medieval theorists numbered eight of them, I to VIII. Each mode centers on its final (the note on which melodies end) and has a reciting tone (tenor), the pitch on which much of the text is sung.
Two systems of names are in use. The Greek-derived one calls the modes Dorian, Phrygian, Lydian and Mixolydian (and their plagal forms with the prefix Hypo-). The Latin one groups each final in an authentic/plagal pair with the names Protus (final D), Deuterus (E), Tritus (F) and Tetrardus (G). So mode I is the authentic Protus and mode II the plagal Protus, and so on.
The 8 modes
| Mode | Greek name | Latin name | Type | Final | Reciting tone | Range |
|---|---|---|---|---|---|---|
| I | Dorian | Protus authentic | Authentic | D | A | D–D |
| II | Hypodorian | Protus plagal | Plagal | D | F | A–A |
| III | Phrygian | Deuterus authentic | Authentic | E | C | E–E |
| IV | Hypophrygian | Deuterus plagal | Plagal | E | A | B–B |
| V | Lydian | Tritus authentic | Authentic | F | C | F–F |
| VI | Hypolydian | Tritus plagal | Plagal | F | A | C–C |
| VII | Mixolydian | Tetrardus authentic | Authentic | G | D | G–G |
| VIII | Hypomixolydian | Tetrardus plagal | Plagal | G | C | D–D |
Authentic and plagal modes
Each final gives rise to two modes. In the authentic mode the melody moves above the final, up to the octave. In the plagal mode (prefix "Hypo-") the melody moves around the final, from a 4th below to a 5th above. Both share the same final but have a different range and a different reciting tone.
The final and the reciting tone
Each mode is recognized by two key notes. The final is the note on which melodies end, the center of rest of the mode. The reciting tone (also called the tenor, tuba or repercussio) is the note on which much of the text is recited, the most repeated one. In the authentic modes the reciting tone is a 5th above the final (with an adjustment in mode III, which uses C instead of B). In the plagal modes it is generally a 3rd below that of the corresponding authentic mode (with an adjustment in mode VIII, which uses C instead of B).
The 8 modes on the staff
Each mode with its full range. The note marked F (in gold) is the final; the note marked R (in blue) is the reciting tone.
Are they the same as the Greek modes?
The names are the same (Dorian, Phrygian, Lydian, Mixolydian), but the systems are different. The church modes are eight medieval modes defined by final and range (with authentic/plagal pairs). The modern Greek modes (also called diatonic modes) are seven and are obtained by playing the major scale from each degree. In notes, the Gregorian Dorian (D to D) matches the modern Dorian. Later, in the Renaissance, Glarean extended the system to twelve modes by adding the Aeolian and the Ionian.