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). The man’s voice was the guide, and from time immemorial the _a_ has been the standard of pitch, by ruling of the ear. (The _A_ below middle C, top line, bass clef). From father to son, from teacher to scholar the tradition of pitch was carried on. The string affected by heat and moisture and by the strain when twanged, never remains accurately to pitch. Although pipes and strings have run a parallel course, we do not find that the lyre players actually cared to refer to pipes as guiding them in setting the pitch. Yet it was the custom, so Plutarch tells us, for _reciters_ and orators to have a pitch pipe sounded by an attendant to keep their voices to a prescribed pitch, and he mentions an ivory pipe being used for the practice. On the contrary it would seem that from the earliest times lyrists of all sorts, and players on stringed instruments of every nation, even up to the present day have found the habit of the ear sufficient for the purposes of their art, that indeed to the soloist, the musical ear relies upon itself for tuning. By the Greeks music as an art was regarded as an aid to regulate by rule the inflections of the voice, to mark the places of emphasis and to define the pauses in the recitation of their epic poetry; and the rhythm of their songs followed strictly laws that had been laid down, innovation was reprehended, and even prohibited. The lyre itself was held subordinate to the voice, accompanying it and filling in the pauses according to a conventional fashion, which the hearers judged, critically and keenly.