Do you perhaps know where the names of the modes/scales come from, why, and since when? They're all greek names, obviously, but why these specific ones? Ionian, Dorian, Phrygian, Lydian, Mixolydian, Aeolian, Locrian.
There's conflicting info on this. Most sources agree that the names as we know them, except "Locrian" (seventh mode), were assigned to the modes by the 16th-Century theorist Heinrich Glarean, aka Henrichus Glareanus. In his 1547 work
Dodecachordus, he analyses the eight Gregorian modes ("authentic" and "plagal"/"Hypo" variants of Dorian, Phrygian, Lydian and Mixolydian), and proposes two new ones, Ionian and Aeolian.
For most of their existence beginning in the Eighth Century AD as the "octoecho" system, these modes were merely numbered (and there was some disagreement over the numbering system between Catholicism and Orthodoxy). Glarean is the first Western (Romance/Germanic) scholar to use these names in music theory, and his names are the ones we still use.
However there is ample evidence that he got them from Ancient Greek music theory dating to the 7th Century BC. Theorists including Pythagoras, Aristoxenos and Ptolemy were among the first to structure pitch and harmony, including the concept of the octave (that the sequence of tones should repeat with every doubling of frequency; "octave" was in turn coined based on its containing two "tetrachords", still a basic tenet of modern music theory).
Among other things, these theories discussed the existence of different "octave species", which could be described in terms of the sequence of notes beginning at the note of a particular name, and these names are pretty familiar; Dorian, Phrgian, Lydian, Mixolydian, Hypodorian, Hypolydian and Hypophrygian. Ionian and Aeolian were used in Greek music theory, but not to describe the modes we currently use them for. In fact, very little of this translates exactly over the nearly two millenia between Aristoxenos's work and Glareans, even though the Greek systems form the basis for the sonic characters Glarean would describe.
This knowledge was lost in the Middle Ages and rediscovered in the Renaissance. Glarean thus certainly knew of the Ancient Greek modes, and assigned the names in a "best-fit" manner to the hexachordal scales he was describing, thus re-standardizing the modes with names that could cross the Schism, where the numeric system of identifying them had been jumbled over the centuries. Again, the underlying theory of the Greeks doesn't translate exactly, however Glarean would have been able to overlay the terms as used for Greek diatonic octave species over the then-state-of-the-art of Western music theory, and fill in a few blanks.
The concept of these modes has since been simplified, in part by the acceptance of the twelve-tone scale which among other things does away with the semantics of whether B can be flat in Guido's hexachordal system. This largely renders the "plagal" variants of the Gregorian modes redundant; if B's always sounded in its "natural" form, then Hypolydian mode is identical to Ionian, Hypomixolydian to Dorian and Hypodorian to Aeolian. Dorian, Phrygian, Lydian and Mixolydian survive, and the last, Hypophrygian (equivalent to Glarean's Hypoaeolian once flatting semantics are ignored), was renamed Locrian sometime in the late 1700s, borrowing from yet another region of Greece and becoming generally accepted as the name of the mode of the seventh diatonic scale degree in the 19th Century.
