Sources

Of course a lot of the material presented below is available in one form or another on the web, but I was also fortunate to be able to call on the extensive knowledge and library of my early-music advisor (and sister-in-law) Hilary Ougham.  I should add that the views expressed here are not necessarily hers and that anything really ludicrous (and some of what follows I now know to be questionable if not downright wrong) is certainly the result of misunderstanding or unfounded speculation on my part.

Primary publications consulted were: R H Hoppin (1978) Medieval Music. NY: Norton; T Knighton, D Fallows (eds, 2003) Companion to Medieval and Renaissance Music. OUP; G Reese (1978) Music in the Renaissance. London: Dent.
 

Organum and before

There was surely music, of some sophistication, in and before the Roman and Hellenic eras, but European culture (including music) had almost to start from scratch in the period following the fall of Rome.

During the first millennium AD, the music we know of was dominated by the voice and subservient to the liturgy.  The single unaccompanied vocal line - plainchant, plainsong, Gregorian chant, liturgical monophony - dates from about the 4th century.

The first polyphonic development out of unison chanting, sometimes just a drone plus melody, is called organum.  The term was introduced by Hucbald (840-c 930) and Regino of Prüm (?-915) in a treatise entitled De Harmonica Institutione.

Musical examples are given in Musica Enchiriadis (Music Manual) and Scholia Enchiriadis (Commentary on the Manual), attributed to Hucbald.

Drones with melodic lines on top may have special significance for the development of jazz practices - see below.  It's interesting that medieval music seems to lack any kind of bass function.  Often the lowest part is only baritone range, or even tenor.  Could this be because people were much smaller then and couldn't have produced low notes even if they wanted to?
 

The appearance of polyphony

The collection known as Winchester Tropers (c 980) is the oldest surviving practical example of polyphony and comprises organum, tropes (new texts and/or notes added to existing music) and sequences (chants performed during the Mass).

Out of drone plus melody came parallel organum (polyphony, heterophony).  Examples in the Enchiriadis show lines at the octave and 5th.  There are some examples of lines a 4th below, but the danger of the forbidden tritone was a limitation on its use.

Next came free (or modified parallel) organum and melismatic organum.

Melisma refers to the singing of several to many notes on a single syllable.  The term florid organum is sometimes used.  It is particularly associated with the School of (St Martial at) Limoges.

Melisma is not common in modern songwriting and, within the American standard cannon, would probably be regarded as poor craftsmanship except where a particular comic or other effect is aimed at (for example "When I'm calling you-oo-oo-oo-oo-oo-oo..." by Friml, Hammerstein, Harbach and Stothart, 1936).  Melisma is, of course, common in, and characteristic of, vocal performance in the folk, blues and soul traditions.
 

Organum becomes more complex

By the 12th century, discant style was being used - syllabic text settings in note-against-note polyphony.

Santiago de Compostela was a centre for this style.  A significant source is the manuscript called the Codex Calixtinus dated around 1140 (Pope Calixtine II died in 1124).  The main entrance of the Cathedral at Santiago de Compostela (Puerta or Portica de la gloria, sculpted by Master Mateo (1161-1217) between 1166 and 1188) shows figures in relief engaged in music-making, including two elders playing the hurdy-gurdy.

The hurdy-gurdy would establish a drone over which the polyphonic line would be sung.  We speculate that this contrast between relative harmonic (vertical) stasis and horizontal (melodic) motion might say something about musical development in jazz.

The major centre of organum in the 12th century was Notre Dame de Paris (rebuilt by Bishop Sully (1163-1200), consecrated 1182).  The composers most closely identified with the Notre Dame style were Perotin and Leonin.

Perotin employed more complex organum triplum and quadruplum forms, but there was still heavy reliance on perfect consonances (unison, fourths, fifths and octaves).

Melismatic organum was succeeded by modal notation, to be replaced in the mid to late 13th century by mensural notation (Franco of Cologne (1260) Ars Cantus Mensurabilis).
 

From organum to Ars Nova

Multi-voice organum was succeeded by so-called conductus, processional non-liturgical compositions, and by the motet, conductus with new words added to upper parts.

With the arrival of the madrigal, we reach the era of Ars Nova.  This dates from about 1313 in Italy and 1320 in France.

Key figures were Philippe de Vitry, Johannes de Muris and, particularly, Guillaume de Machaut (c 1300 - c 1377).

As the 14th century proceeded, the influence of Notre Dame organum lapsed, to be supplanted by the Mass (de Machaut was composer of one of the earliest examples, some time before 1365, the four-voice Messe de Nostre Dame).

de Machaut's music seems pretty far out, even to a jazz musician.  To me it sounds halfway between modal polyphony and true cadential progression.  As I write this I'm listening to a performance of 4 of his ballades and fascinated by the way intertwining lines hit on odd oblique chords, sometimes at points of repose, finally resolving on plain root-fifth just when it seems the harmonies are out of control.  It reminds me of orchestrations by Charles Mingus or Duke Ellington at their most eccentric.
 

The secular traditions

The troubadours, composers and performers of songs, began to flourish during the 11th century and the style was still being imitated in the 13th. Troubadour songs deal mainly with secular themes of chivalry and courtly love.

Other similar performers in the same period went by the names of wandering scholars, goliards, jongleurs or Minnesingers.

Records of troubadour songs are limited - it's estimated that fewer than 300 out of 2500 melodies survive.  Troubadour songs were usually monophonic and often followed broad rules, such as those set out in Leys d'amors (compiled in 1340).

Cambridge Songs is an 11th Century manuscript illustrative of the tradition.  Carmina Burana comprises songs from the late 13th century and earlier.

It is assumed that these songs were performed with instrumental accompaniment, but musical sources record only the voice part and so the nature of the instruments used and what they played represent a vanished culture.

Knighton and Fallows (2005) in their Companion to Medieval and Renaissance Music state: "The dearth of manuscript evidence for instrumental music in the Middle Ages is both astonishing and mysterious"

These authors also present a particularly pertinent quote from the lutenist Crawford Young: "To what extent is pre-Baroque notation unlike its modern counterpart?  It was often used to preserve a generic version of a piece of music - similar perhaps to a jazz musician's 'fake book'" [my italics]
 

The beginnings of harmony

In considering what form instrumental accompaniment might have taken in the Middle Ages, Knighton and Fallows (2005) suggest that "drones - sustained notes in the manner of melismatic organum - are (still another) possibility".

The general view is that pedals and drones stand at the origin of the conception of harmony.

Until the 10th century, harmony meant parallel organum, based on the octave, 5th and 4th.

From the late 10th century "imperfect" intervals (3rds, 6ths) began to appear, and by the 12th century there was increasing freedom in the form of passing notes.

These trends continued and expanded up to the early 15th century (John Dunstable (d 1455) a significant figure at this time).

By the late 16th century, the era of madrigals (Giovanni Palestrina (1525-1594) a key figure), there was free movement of parts, polyphony and recognisable key signatures, although there remained a lot of wandering indeterminate tonality and use of modes.

The earliest instances of continuo and figured bass date from the late 16th century and they had become well established by the time of JS Bach (1685-1750).

Finally the principles of harmony (including inversions) in the recognised modern sense became formalised in Traité de l'Harmonie réduite à ses principes naturels (1726) by Jean Philippe Rameau (1683-1764).

Figured bass is a very neat way of notating inversions.  For example in the root position of the C major triad, C to E is a third and C to G is a fifth, so it is represented in figured bass as ⁵₃.  The first inversion becomes ⁶₃ and the second ⁶₄ (work it out).  Figured bass and continuo clearly functioned somewhat like chord progressions and the rhythm section in jazz, though jazz chord symbol notation is probably more limited than figured bass in conveying information about voicings and harmonic movement.
 

The Cecilian Movement and similar

Periodically the urge to return to simpler (which often means earlier) times and styles wells up in culture, and music is no different.

The Cecilian Movement (named for St Cecilia, patron saint of music) in the 19th century wanted to reclaim liturgical music from the operatic and re-establish the pre-Baroque principles of organum, non-cadential harmony and minimal instrumentation.

Some composers of the Wagnerian era were responsive, notably Bruckner whose Os Justi - Gradual for 8-part Choir would not have been out of place in the Notre Dame of 600 years previously.

Another example of the recursive principle in musical history is Stravinsky's engagement with Neoclassicism in the years after World War I - described as the repentance of a modernist sinner who returned to the formalities of the 18th Century.

Neoclassicism endures to the present day, in the shape of composers like Arvo Pärt and John Tavener.

Jazz has its own neoclassical movement, led by Wynton Marsalis at the Lincoln Center in New York.  Some find its reverence for the "classical" era and performers and its treatment of 1965 onward as a barren period of jazz history as unnecessarily regressive and reactionary.  Others believe it has saved jazz from disappearing without trace into the black holes of fusion and free music.

Jazz is an awfully young musical form to have already spawned a neoclassical movement, but in fact it has long been riven by tribal disputes, notably between the reverential re-creators (for example the Ken Colyer-type revivalists) and the boundary-pushers (Ornette Coleman, to name someone guaranteed to raise neoclassical bloodpressures).  But somewhere in this confused picture comes a creation like Kind of Blue which simultaneously revolutionises the whole direction of the music and conceptually seems to link to a tradition that does not just pre-date jazz but belongs somewhere on the medieval side of the Baroque.  Its non-cadential harmonies, sustained drone-like atmospheres and modal structures are almost Cecilian.  Maybe its link to the infancy of Western musical evolution explains why Kind of Blue is a widely-used source for elementary jazz education.