ries lyres of seven and eight strings were employed. And, by the
expiration of a thousand years, they had advanced to their "great
system" of the double octave. Through all which changes there of course
arose a greater heterogeneity of melody. Simultaneously there came into
use the different modes--Dorian, Ionian, Phrygian, AEolian, and
Lydian--answering to our keys; and of these there were ultimately
fifteen. As yet, however, there was but little heterogeneity in the time
of their music.

Instrumental music during this period being merely the accompaniment of
vocal music, and vocal music being completely subordinated to words, the
singer being also the poet, chanting his own compositions and making the
lengths of his notes agree with the feet of his verses,--there
unavoidably arose a tiresome uniformity of measure, which, as Dr. Burney
says, "no resources of melody could disguise." Lacking the complex
rhythm obtained by our equal bars and unequal notes the only rhythm was
that produced by the quantity of the syllables and was of necessity
comparatively monotonous. And further, it may be observed that the chant
thus resulting, being like recitative, was much less clearly
differentiated from ordinary speech than is our modern song.

Nevertheless, in virtue of the extended range of notes in use, the
variety of modes, the occasional variations of time consequent on
changes of metre, and the multiplication of instruments, music had,
towards the close of Greek civilisation, attained to considerable
heterogeneity--not indeed as compared with our music, but as compared
with that which preceded it. As yet, however, there existed nothing but
melody: harmony was unknown. It was not until Christian church-music had
reached some development, that music in parts was evolved; and then it
came into existence through a very unobtrusive differentiation.
Difficult as it may be to conceive _a priori_ how the advance from
melody to harmony could take place without a sudden leap, it is none the
less true that it did so. The circumstance which prepared the way for it
was the employment of two choirs singing alternately the same air.
Afterwards it became the practice--very possibly first suggested by a
mistake--for the second choir to commence before the first had ceased;
thus producing a fugue.

With the simple airs then in use, a partially harmonious fugue might not
improbably thus result: and a very partially harmonious fugue satisfied