Medieval modes are the basis of music theory from that time period, and find their roots in Greek musical theory. Codified in the 10th century, they were the blueprint for sacred chants and for many secular works as well. When Boethius composed De institutione musica on the musical traditions of the Greeks, around 500 A.D., he could never have believed how brutally his subsequent music theorists would misunderstand him. Mixing up the names, they called the lowest mode in the system (A-a) hypodorian, which was originally the highest, and subsequently misnamed everything else, in addition to adding an extra mode, hypomixolydian.
Medieval modes are made up of arrangements of whole and half steps in relation to the final, the main note in the mode and typically the final note in the melody. Modes come in pairs according to their final, but differ according to the range. For example, Mode 1, Dorian, has its final on D, and has a range from a whole step above the final to an octave above it. Mode 2, Hypodioran, has its final on D as well, but its range is deeper, a fourth/fifth below D to a fifth/sixth above it. The odd modes were known as authentic, and their lower companions were given the title plagal. What gave each mode its distinctive flavor was the unique set of whole and half steps which comprised it, based in theory off the Greek system
of modes which were comprised of tetrachords. The note most frequently sounded in a given mode was known as the tenor, or reciting tone, and served as the gravitational center for the mode. Most chants moved within the given ranges, lingered on the tenor and moved to a cadence on the final.
Nevertheless, despite poor translations of ancient Greek musical practices, many of their ideas have carried over into Western traditions. For example:
- melody was intimately linked with rhythm and the flow of words
- musicians relied on aural tradition to convey new music
- philosophies influenced musical practices and beliefs about the nature of music and its influence on human nature
- music theory was founded on scientific principles of acoustical physics
One can easily see that even today, most vocal music depends on the rhythm and flow of words to form the melody, and aural translation of music is the most natural way to learn music. Mothers are convinced that making their children listen to Mozart will increase their IQ, and Western musical theory still follows the basic acoustical properties based around the harmonics of the octave, the fifth and the third.