As an initial introduction to the principal names and divisions of the Ancient Greek tone system this article will give a depiction of the "perfect system" or
systema teleion, which was elaborated in its entirety by about the turn of the 5th to 4th century
BCE. The
diagram at the right reproduces information from . It shows the common ancient
harmoniai, the
tonoi in all
genera, and the system as a whole in one complete map. (Half-sharp and double-sharp notes not used with the depicted notes are omitted.) The central three columns of the diagram show, first the modern note-names, then the two systems of symbols used in ancient Greece: the vocal symbols (favoured by singers) and instrumental symbols (favoured by instrument players). The modern note-names are given in the
Helmholtz pitch notation, and the Greek note symbols are as given in the work of . The pitches of the notes in modern notation are conventional, going back to the time of a publication by in 1840; in practice the pitches would have been somewhat lower. The section spanned by a blue brace is the range of the central
octave. The range is approximately what is now depicted on a modern music staff and is given in the
graphic below, left. Note that Greek theorists described scales as descending from higher pitch to lower, which is the opposite of modern practice and caused considerable confusion among Renaissance interpreters of ancient musicological texts. The earliest Greek scales were organized in
tetrachords, which were series of four descending tones, with the top and bottom tones being separated by an
interval of a fourth, in modern terms. The sub-intervals of the tetrachord were unequal, with the largest intervals always at the top, and the smallest at the bottom. The 'characteristic interval' of a tetrachord is its largest one. The
Greater Perfect System (
systema teleion meizon) was composed of four stacked tetrachords called (from lowest to highest) the
Hypaton,
Meson,
Diezeugmenon and
Hyperbolaion tetrachords. These are shown on the right hand side of the diagram. Octaves were composed from two stacked tetrachords connected by one common tone, the
synaphe. At the position of the
paramese, the continuity of the system encounters a boundary (at b-flat, b). To retain the logic of the internal divisions of the tetrachords and avoid the
Meson being forced into three whole tone steps (b–a–g–f), an interstitial note, the
diazeuxis ('dividing'), was introduced between the
paramese and
mese. This procedure gives its name to the tetrachord
diezeugmenon, which means the 'divided'. To bridge the inconsistency of the
diazeuxis, the system allowed moving the
nete one step up, permitting the construction of the
Synemmenon ('conjunct') tetrachord, shown at the far left of the diagram. The use of the
Synemmenon tetrachord effected a modulation of the system, hence the name
systema metabolon, the modulating system, also called the
Lesser Perfect System. This was considered apart, built of three stacked tetrachords—the
Hypaton,
Meson and
Synemmenon. The first two of these are the same as the first two tetrachords of the Greater Perfect System, with a third tetrachord placed above the
Meson. When all these are considered together, with the
Synemmenon tetrachord placed between the
Meson and
Diezeugmenon tetrachords, they make up the
Immutable (or Unmodulating)
System (systema ametabolon). The lowest tone does not belong to the system of tetrachords, as is reflected in its name, the
Proslambanomenos, the adjoined. In sum, it is clear that the Ancient Greeks conceived of a unified system with the tetrachord as the basic structure, but the octave as the principle of unification. Below is an elaboration of the mathematics that led to the logic of the system of tetrachords just described. ==The Pythagoreans==