Note 25 — § 26. The Ethos of the Genera and Species.

Ptol. Harm. ii. 6. After drawing a distinction between difference of key as affecting the whole of a melody or piece of music and as a means of change in the course of it—the distinction, in short, between transposition and modulation proper—he says of the latter: hautê de hôsper ekpiptein autên (sc. tên aisthêsin) poiei tou synêthous kai prosdokômenou melous, hotan epi pleon men syneirêtai to akolouthon, metabainê de pê pros heteron eidos, êtoi kata to genos ê kata tên tasin. That is to say, the sense of change is produced by a change of genus or of pitch. A change of species is not suggested. So Dionys. Hal. De Comp. Verb. c. 19 hoi de ge dithyrambopoioi kai tous tropous (keys) meteballon, Dôrikous te kai Phrygious kai Lydious en tô autô asmati poiountes; kai tas melôdias exêllatton, tote men enarmonious poiountes, k.t.l.