This fascinating information can be found at http://public.wsu.edu/~delahoyd/greek.music.html. The following is an excerpt:
Archaeological evidence and written accounts, both historical and literary, show that music was vital to ancient Greek culture. Choruses in the Greek plays were sung, and music was central to religious and state ceremonies and to social rituals such as weddings, funerals, banquets, etc. The Homeric epics were probably “sung to formulaic melodies” (Bonds 4). But memorization was key to performance, not written notation, so only about 45 pieces of music, mostly fragments, survive from the time in bits of papyri and marble, and in documents copied in the Middle Ages and Renaissance.
More material survives regarding music theory than actual music. Pythagoras supposedly discovered the connection between music and mathematics — that the intervals of octave, fifth, and fourth are “perfect consonances” because they can be expressed (and replicated) by the ratios 2:1, 3:2, and 4:3, respectively. Later Pythagoreans credited him also with the notion of the “music of the spheres” — the idea that the rotation of the planetary spheres creates an inaudible harmony. Music was part of the quadriviumin the liberal arts, primarily because, along with arithmetic, geometry, and astronomy, music’s mathematical nature could be emphasized. “Practicing musicians, although widely admired for their performances, were not considered among the intellectual elite: they could entertain, but they could not edify their audiences” (Bond 12).
The belief that music could govern the human soul and had power over behavior is illustrated in the story of Orpheus and Eurydice, in the story of Odysseus and the Sirens, and elsewhere. This “doctine of ethos” — the “belief that music has the power to elevate or debase the soul” (Bond 10) — led Aristotle to note the moods created by various modes and Plato to recommend restrictions to certain modes of music on the part of youths. Music in the Dorian mode bolstered courage and in the Phrygian mode fostered thoughtfulness (an early form of Mozart for infants). Plato even warned about the politically subversive potential of music (and he was right — look what happened with the jitterbug).
Bonds, Mark Evan. A History of Music in Western Culture. Upper Saddle River, NJ: Prentice Hall, 2003.
Musique de la Grèce Antique. Atrium Musicae de Madrid. CD. Arles: Harmonia Mundi, 1979. HMA 190101015.
Palisca, Claude V., ed. Norton Anthology of Western Music, Volume I: Ancient to Baroque. 4th ed. NY: W.W. Norton and Co., Inc., 2001.