A mode is a kind of “do-re-me” experience, like a modern musical scale. Modern scales are based on what are called church modes (because they were used in church music). Before there were pianos and organs, a note’s relationship to any other note was somewhat changeable. There were stringed instruments (like the harp, psaltery, and lyre) whose tuning could be changed in a matter of moments or even accidentally, and flutes, whose tuning was entirely dependent upon hole placement and the length of the instrument, and was super easy to get wrong.
Before the 10th century, music was learned by memory because there wasn’t notation, and presumably, melodies changed and mutated with each individual who tried to learn and with every skilled performer who messed with it a little for the pleasure of it. Patterns emerged. Then, as now, people enjoyed recognizing familiar elements and the patterns began to be expected. In modern music, this is still true, with cadences and a certain pattern of chords that indicate that the end is approaching. Ever notice that people sing along when it’s familiar? That’s exactly what I mean.
You might think of modes like punctuation. Certain sounds, like at the end of a sentence or question, indicate something specific to the listener. This is also true with melodies. As music evolved, certain patterns were thought of as pleasing and were re-used and re-formulated; these patterns and their elements became the modes.
The specific modes were not really a concept until the 10th century when exact pitch notation and the Guidonian system (you can read more about this on my blog entry The Guido’s Hand Seminar ) came into being in Europe. This meant that a song started on the same pitch every time it was sung rather than adapting to whatever pitch suited the singer’s comfort. But once modes were invented as they tried to document the existing chants, they found that the majority of the chants fit into the new theoretical system of modes. How wonderfully convenient!
In the end, modes are easy enough to define in modern terms: modes are a series of notes in an octave that is distinguished by the placement of half and whole steps. In other words, if you moved do-re-mi around on the piano, always playing eight notes in a row, and only playing the white notes, you could play each of the eight modes.
Just for contrast, later music, such as that from the Classical or Romantic eras, uses only two modes, major and minor. One modern scale is formed the same way as another, with the half steps (the black keys on the piano) in identical places, no matter which note it starts on. Depending on how you look at it, modern scales are way simpler (because there are only two of them) and way more complicated (because you have to memorize which notes are part of which scale or where the half-steps are). Each mode has a distinctive sound to it, unlike modern scales where, unless you have perfect pitch, one major scale sounds much like any other.
There are two forms of modes: authentic and plagal. These names come from the four original modes Dorian, Phrygian, Lydian, and Mixolydian and a near relative of each, beginning a fourth lower and using the same series of notes called Hypodorian, Hypophrygian, Hypolydian, and Hypomixolydian. In the middle of the 16th century, mode placement and transposition created four new modes: Ionian and Hyperionian (ending on C), and Aeolian and Hyperaeolian (ending on A). Ionian sounds just like a C major scale, in case you were wondering, and is the usual do-re-me arrangement.
Modes were not regarded as repeatable from octave to octave, like a modern scale is. A single octave of the mode represents the normal range for a melody in that mode. Stretching beyond the octave was simply not done. Authentic modes seldom have melodies that drop below the starting note (or the final note) by more than a single step; plagal modes can wander further below and a step above the octave.
In the 10th century, as theorists tried to formulate a strategy, they found that they could relate their discoveries into the Greek system of modes as described by Boethius and later Latin writers. That’s why the modes have Greek names, although nothing else about them is Greek. (It is humorous to note that the names were misapplied, but that’s a subject for another day.)
In the first half of the 12th century, the Cistercians amended some of the chants to make them fit into the new modal system. The Cistercians, a particularly severe and fundamentalist order of Catholicism (Bernard of Clairvaux was a member), took a biblical passage literally and deigned that no music should extend beyond the ten strings of a psaltery. To do this, they had to transpose some chants or parts of chants.
As scholars tried to fit existing chant into the parameters of the nascent notation system, they struggled with getting the notes and intervals to sound the same. This was because they hadn’t invented all those black keys on the piano—the sharps and flats. Music was written without accidentals other than the occasional B-flat. Even well past Bach’s time in the 18th century, B-flat was considered the ”devil’s note” and its use was restricted in the extreme. For instance, you could only have a B-flat on the way up a scale. B had to return to its natural state on the way back down. At any rate, the only accidental in Medieval times was a B-flat, so they had to move some chants around, squeeze them by force it seems, in order to get them into the modes once they’d established what those were.
Before the invention of the staff, identifying the mode didn’t matter. The correct intervals were applied wherever they were sung within a singer’s range—the starting note as you and I know it simply didn’t matter. Once the lines of the staff forced the invention of absolute pitches (where a C is always a C), elements like a singer’s range, the placement of accidentals, and whether a chant was joyful or sad became relevant.
Establishing the modes freed composers from centonization, which means using an existing melody to create a new song. Prior to music notation, melodic themes made it possible to learn a wide variety of chants by rote memorization. You only had to learn the new words and stick them into the familiar melody. After the staff’s invention, there were more options and new melodies were created with wild abandon. Okay, maybe not wild abandon, but with the full freedom that having an outline provides.
After notation was invented and the modes put into common practice, chants were constructed so that the third and fifth notes were emphasized in addition to the first note of the mode. Phrases begin and end on these notes more than on any others. This is foreshadowing for the more modern chord.
Okay, so that’s church modes in a nutshell. Next up, rhythmic modes.
Early Medieval Music Up to 1300, edited by Dom Anselm Hughes, Oxford University Press, London, 1954
A History of Western Music (8th edition), J. Peter Burkholder, Donald Jay Grout, Claude V. Palisca, W. W. Norton & Company, New York, 2010
Medieval Music, Richard H. Hoppin, W. W. Norton & Company, New York, 1978