Modes

Music in the middle ages

Western music notation, (almost) as we know it, was the invention of Guido d'Arrezzo, a Benedictine monk, who was born arround 991 or 992 A.D. His objective was to reduce the time needed by monks to learn and remember a Gregorian chant. He was remarkably successful.

Then, and for the ensuing half millennium or so, the music was sung in one of eight 'ecclesiastical modes', listed right. They were described as the first to the eighth mode, and the Greek names attached in an attempt, mistaken as it turned out, to connect with the practice in ancient Greece. Nevertheless the names have stuck and are the ones used today.

These modes predate today's familiar major and minor modes by hundreds of years, and so we shall attempt to define them in their own terms, rather than by their relationship to modern major/minor music with which we are more familiar.   Each mode uses seven notes, which we can think of as the set { A B C D E F G }, but the notes are used in different ways - hence the name 'modes'.

The modes

Each mode has its own 'final' note - the note which felt like 'home'. (The equivalent of what would nowadays be denoted the 'tonic' of a major key.)

For the 'authentic' modes, the finals are: Dorian D, Phrygian E, Lydian F, Mixolydian G.

The 'plagal' modes (Hypodorian, Hypophrygian, ...) have the same final as their authentic partner, but where the authentic modes had a range of roughly an octave from final to final, the plagal modes had a range with the final in the middle.

The important thing is that for a piece in one of these modes, the 'final' really does have to feel like home.  In the western Christian music of the middle ages this was the most natural thing in the world, and having 'C' as the final (as if playing in C major), was unheard of!    Nowadays the modes are less familar and it may require a mental leap.

Exercise: take out your instrument, decide on a 'final', and improvise using only the set of notes {A B C D E F G} until you really feel deeply that your chosen 'final' is home!

Some comments

The third from the final in Dorian and Phrygian mode is a minor third. In Lydian and Mixolydian it is a major third. This distinction is important in their subsequent development.

Dorian was the most popular of the mediaeval modes. A now 'traditional' piece in Dorian mode is the sea shanty 'What Shall We Do With The Drunken Sailor': 

Phrygian mode can sound very Spanish, and today is sometimes described as the 'Spanish minor'.

Musica ficta

Musica ficta and musica recta

As time went on a certain amount of 'chromaticism' developed, introducing more pitches than just the 7 considered to be part of the mode.  The term for this (in the period roughly 1200-1600 A.D.) was 'musica ficta'  - using 'false' notes in addition to the 'correct' notes ('musica recta') of the mode.   These extra notes were not originally marked with accidentals - singers and players had to know what to do.   (Modern editions of old music are now usually helpful enough to show accidentals!)  Today's major and minor modes evolved via musica ficta.

Evolution of major and minor modes

Take the Lydian and Mixolydian modes - the ones with the major third.   In the Lydian mode the 4th is (uniquely) an augmented 4th from the final (the interval F to B).  If you wanted to avoid this, then flattening the 4th, replacing a B by a B♭,  might be a good idea.   In the Mixolydian mode, stepping from the 7th to the final (F to G), sounds more final if the 7th is sharpened (so that the interval becomes F♯ to G).   If we were to go as far as to make these replacements (rather than just adding the chromatic notes as alternatives) then we'd obtain scales FGAB♭CDEF and GABCDEF♯G - the scales of F major and G major respectively.  This (although perhaps a simplification) is essentially the way that the 'major' mode evolved.

Equally if we take the Dorian and Phrygian modes, chromatic additions and adjustments have a similar effect.  If we introduce a sharpened 7th degree and a flattened 6th to the Dorian scale we obtain DEFGA(B♭/B)(C/C♯)D  - the notes of Dminor with its characteristically variable 6th and 7th degrees.

What did musica ficta do for us?

It seems that musica ficta starts out as an idea to decorate modal music with the occasional chromatic note, but ends up by blurring the whole modal schematic, and paving the way for a completely new music in major and minor keys!

More modes

Aeolian and Ionean

In 1547 the Swiss music theorist Henricus Glareanus (or Heinrich Glarean, or Heinrich Loris) 1488-1563 published his 'Dodecachordon' in which the twelve modes of the title were the above eight and four new ones: Aeolian, Hypoaeolian, Ionean, and Hypoionian.

In terms of our set of notes above { A B C D E F G }, the finals of these are Aeolian: A, and Ionian C.  An Ionean scale therefore looks just like the major scale and an Aeolian scale looks like the natural minor scale.   (It is a mistake, however, to think that Major and Minor derived from Ionean and Aeolean modes.  By 1547 musica ficta was a fact of life, and Major, Minor, Aeolian, and Ionean all arose in its wake.)

Locrian

At this point we have the eight original modes, and four more (leaving Major and Minor aside for the moment) in pairs, each pair having a different final from the 7 notes. The only note we can't have as a final is B. The reason is that if we choose B as a final, the 5th note, F, is a diminished 5th. (All the modes thus far have a perfect 5th.)

For completeness's sake, the modes with the notes A B C D E F G and the final B have names: Locrian and Hypolocrian. But they were never contenders for making music (well at least not until the modern era, where just about everything has been tried)!

Summary

We now have 7 authentic modes (and 7 plagal partners) which use the set of notes {A B C D E F G} (again leaving Major and Minor aside for the moment). The finals and the corresponding authentic modes are

After the modal era

By the time of J S Bach (1685-1750) major and minor modes were well established and Bach famously published his pieces for well-tempered Klavier presenting music in all possible key signatures.   This is the beginning of what is called the 'period of common practice' in which music in major and minor modes, modulating into different keys, quite generally followed a pattern very different from the earlier modal music.  (The common practice period is thought of as ending at the beginning of the 20th century, with radical diversions into 12-tone serialism and other radical forrays into breaking the mold.  Though in truth, much music, even today, follows the general patterns of the common practice period.)  Modal music was largely forgotten over a period of 300 years or so.

Ecclesiastical modes rediscovered

Then, around the 1960s, various musicians rediscovered the old modes.

Some modern terminology

A this point we need to introduce some modern terminology.

The important distinguishing feature of the various modes is the pattern of tone and semitone intervals in relation to the final. For example Dorian mode (back to musica recta!) has semitone intervals between the 2nd and 3rd notes from the final, and between the 6th and 7th. The semitones of Phrygian mode are between the final and the 2nd and between the 5th and 6th.  And so on. 

We can transpose the music and its mode does not change. So these days the modes as tabulated with the notes above are denoted D-Dorian, E-Phrygian, F-Lydian, G-mixolydian, A-Aeolian, B-Locrian and C-Ionian.   If we transpose them up a tone we get: E-Dorian with notes EF♯GABC♯DE and final E;  F♯-Phrygian with notes F♯GABC♯DEF♯ and final F♯; and so on.    This is all in a modern parallel with major and minor nomenclature where a piece in the major mode (for example) with C as the tonic is in C-major, and if transposed so that F is the tonic is in F-major.

Modes in the 20th and 21st centuries

An interesting facet of the rediscovery of modes is that it seeems to have happened in jazz, and popular music around the same time  (though classical composers may have been quietly using modes for some time).  In jazz, Miles Davis's 1959 album 'Kind of Blue' is seminal. Wikipedia says of the first track, "So What", 'It is one of the best known examples of modal jazz, set in the Dorian mode and consisting of 16 bars of D Dorian, followed by eight bars of E♭ Dorian and another eight of D Dorian.'    The use of modulating Dorian mode with two different 'finals' means that modal music in the 20th century was already a blend of ideas of mediaeval modes, and the subsequent development of modulation.   So this is not just a regression to the middle ages.   In popular music the Beatles' 'Eleanor Rigby' is often cited as being in Dorian mode.

In jazz it is now popular to talk about 'modes of the major scale' when referring to sequences of notes in step starting at some point on a major scale, though this is quite far from the original concept of modes, in which a mixolydian scale was not a permutation of the notes of a major scale, but rather a major scale was a chromatically altered mixolydian scale. Thus while mediaeval modes have been rediscovered, only some of their original attributes have been retained, and new possibilities, such as modulation, have developed. The revived modes go by the same names, but the emphasis and their characteristics are very different.