> In the meantime I came across this item from Theodore
> Finney's "History of Music" wherein he says: "That tenative
> perception of the naturalness of the diatonic genus was the
> first great step in the direction of modern tonality. Had the
> Greeks settled on the enharmonic genus (there were three
> types of tetrachords: diatonic, chromatic, and enharmonic)
> for instance, the whole course of Western musical development
> would have been much different. We might have inherited a
> music similar to that of India."
> I don't quite understand what Finney means by this, but I
> would be interested to know how it was that India's music
> remained where it was and Europe went on to develop Brahms,
> Beethoven, Schubert etc.. Great post, btw.
He's referring to Ptolemaic tuning discoveries and Pythagorean discoveries of the harmonic series, the 3/2 relationship of the fifth to the tonic, that resulted in the western scales based on half step / whole step intervals. Indian music uses smaller step intervals. Alot of notes on a sitar for instance are inbetween adjacent piano keys. Western classical music could not develop from such a system. Symphonic music as it developed is vertically oriented stacked tones modulating chord progressions through different keys. Indian music doesn't change key, the intervals are not equidistant and would thus be out of tune with each other. Even with Pythagoras system it took the tuning change of the Baroque period to prepare the way for key modulation. Intervals were made equidistant thus each was made slightly out of tune with nature in order that as keys were modulated they were kept in tune with each other. The Fifth remains true to nature as are all Fourths in relationship 4/3 apart from the interval from B to F which is a semitone smaller and F to B, a semitone larger. I wonder if those keys were forbidden by the church as the Fourth wasn't perfect, nearer to the tritone or Devil's interval.
Diatonic refers to what we call Major Scales and also includes the modes, although several of them are themselves minor, they're built on major scales. Plato avowed that only the Phrygian and Locrian modes were legitimate for music. These are the most foreign modes to western ears being built off the Third and Seventh of the scale respectively they both contain the most dissonant interval the Minor Second.
Chromatic refers to music that crosses keys, music with more than the usual two half steps, much use of the tritone, passing tones, etc. Bartok is a good example, as is much of the Balkan and Slavic folk music he drew on or his pop music acolytes such as Fripp's King Crimson. There's a humorous moment in Sayle's Return of the Secaucus Seven where someone is expounding on just this sort of thing and another character says dismissively "heavy metal goes to college".
Enharmonic can mean different names for the same note, for instance E# and F or Cb and B are enharmonics. It can also refer to music built on smaller than half step intervals.
Some just intonation oriented players are less than fond of Pythagoras. The violinist, film maker, one time member of Lamonte Young's Theatre of Eternal Music, Tony Conrad makes music based on very specific microtonal tunings. In the liner notes of a cd he released some years ago he went on this amusing rant about what a fascist Pythagoras was to straightjacket us within this totalitarian musical system.