"equable" or "even diatonic" as sounding foreign or rustic, and its neutral seconds are reminiscent of scales used in Arabic music. It is based on an equal division of string lengths (thus presumably simple to build and "rustic"), which implies a harmonic series of pitch frequencies: hypate parhypate lichanos mese 4:3 11:9 10:9 1:1 | 12:11 | 11:10 | 10:9 | -498 -347 -182 0 cents Byzantine music In Byzantine music most of the modes of the octoechos are based on the diatonic genus, apart from the second mode (both authentic and plagal) which is based on the chromatic genus. Byzantine music theory distinguishes between two tunings of the diatonic genus, the so-called "hard diatonic" on which the third mode and two of the grave modes are based, and the "soft diatonic" on which the first mode (both authentic and plagal) and the fourth mode (both authentic and plagal) are based. The hard tuning of the diatonic genus in Byzantine music may also be referred to as the enharmonic genus; an unfortunate name that persisted, since it can be confused with the ancient enharmonic genus. Chromatic Aristoxenus describes the chromatic genus () as a more recent development than the diatonic. It is characterized by an upper interval of a minor third. The pyknon (πυκνόν), consisting of the two movable members of the tetrachord, is divided into two adjacent semitones. The scale generated by the chromatic genus is not like the modern twelve-tone chromatic scale. The modern (18th-century) well-tempered chromatic scale has twelve pitches to the octave, and consists of semitones of various sizes; the equal temperament common today, on the other hand, also has twelve pitches to the octave, but the semitones are all of the same size. In contrast, the ancient Greek chromatic scale had seven pitches (i.e. heptatonic) to the octave (assuming alternating conjunct and disjunct tetrachords), and had incomposite minor thirds as well as semitones and whole tones. The (Dorian) scale generated from the chromatic genus is composed of two chromatic tetrachords: E−F−G−A || B−C−D−E whereas in modern music theory, a "chromatic scale" is: E−F−G−A−B−C−D−E Shades The number and nature of the shades of the chromatic genus vary amongst the Greek theorists. The major division is between the Aristoxenians and the Pythagoreans. Aristoxenus and Cleonides agree there are three, called soft, hemiolic, and tonic. Ptolemy, representing a Pythagorean view, held that there are five. Tunings Theon of