thus comprising fourth, fifth and octaves according to our terminology, though doubtless the god was ignorant of such things. Emerging from the mists of fable we arrive at traces of a period at which it is said the octave became disused, and nothing remained but the fourth in its rudimentary condition, divided next into two steps, and after that separated in three divisions resulting in an interval comprising two tones and a lesser tone, or two steps and a half, so that the whole is marked by four sounds; this series was then undesignated, but after a time a stage was arrived at when it was designated, and known thereafter by the word “tetra” signifying “four” and the inclusive system was called a tetrachord, and therefore the commencement of the evolution of a musical scale.
The ending of the word in “chord,” has given rise to the notion of a chord as of harmony, and again of cords as another name for the strings. But these are misconceptions, the meaning of “tetrachord” is, a series of four sounds, in an order of succession so that the extreme sounds comprise a fourth. The terms fourth, and fifth, and octave, are quite artificial, are signs founded on vision or the counting of the strings of the lyre; the fourth in music is not a fourth part of anything, is not a fourth part or proportion of the octave, it was called by the Greeks “diatessaron,”—right through or over, four.
One most ancient form may be represented thus, considering the extreme sounds to embrace the interval,—
e ‿ f——a
it was the initiatory stage afterwards completed as,—
e ‿ f——g——a
only that it should be read from right to left, because with the Greeks the reading was from the high note downwards thus—
a——g——f ‿ e
to us occularly confusing, yet it was the way of Greek thought.
(The sign —— indicates whole tone, and ‿ semitone).