with the symmetry of the body as making rhythmical gesture
necessary; or more particularly with the conditions of work,
which, if it is skilled and well carried out, proceeds in
equal recurring periods, like the swinging of a hammer or an
axe. But it appears that primitive effort is not carried on
in this way, and proceeds, not from regularity to rhythm, but
rather, through, by means of rhythm, which is made a help, to
regularity. Again, it is said that work can be well carried
out by a large number of people, only in unison, only by
simultaneous action, and that rhythm is a condition of this.
The work in the cotton fields, the work of sailors, etc.
requires something to give notice of the moment for beginning
action. Rhythm would then have arisen as a social function.
Against this it may be said that signals of this kind might
assist common action without recurring at regular intervals,
while periodicity is the fundamental quality of rhythm. Thus
this theory would explain a natural tendency by its effect.

Looking then, in accordance with the principle stated above,
for deeper conditions, we find rhythm explained in connection
with such rhythmical events as the heart beat and pulse, the
double rhythm of the breath; but these are, for the most part,
unfelt; and moreover, they would hardly explain the predominance
of rhythms quite other than the physiological ones. Another
theory, closely allied, connects rhythm with the conditions
of activity in general, but attaches itself rather to the
effect of rhythm than to its cause. Thus we are reminded of
the "heightened sense of expansion, or life, connected with
the augmentation of muscular movements induced by the more
extensive nervous discharges following rhythmic stimulation."<1>