beat always coming on one foot, and the light beat on the other,
would soon tire the dancer; therefore some way must be found
to make the strong beat alternate from one foot to the other.
The simplest, and in fact almost the only way to do this,
is to insert an additional short beat before the light beat.
This gives us [- ' -] or [4. 8 4], the dactyl in poetry.

We have, moreover, here discovered the beginning of form, and
have begun to group our musical tones in measures and phrases;
for our second dactyl is slightly different from the first,
because the right foot begins the first and the left foot the
second. We have two measures [(4. 8 4 | 4. 8 4)]
[(- ' - | - ' -)]
and one phrase, for after the second measure the right foot
will again have the beat and will begin another phrase of two
measures.

Carry this theory still further, and we shall make new
discoveries. If we dance in the open air, unless we would dance
over the horizon, we must turn somewhere; and if we have but a
small space in which to dance, the turns must come sooner and
oftener. Even if we danced in a circle we should need to reverse
the motion occasionally, in order to avoid giddiness; and this
would measure off our phrases into periods and sections.

Thus we see music dividing into two classes, one purely
emotional, the other sensuous; the one arising from the language
of heroes, the other from the swaying of the body and the patter
of feet. To both of these elements, if we may call them so,
metre and melody brought their power; to declamation, metre