II

The two great factors of music are rhythm and tone-sensation,
of which rhythm appears to be the more fundamental.

Rhythm is defined in general as a repeating series of time
intervals. Events which occur in such a series are said to
have rhythm. In aesthetics, it is the periodic recurrence of
stress, emphasis, or accent in the movements of dancing, the
sounds of music, the language of poetry. Subjectively it is
the quality of stimulation due to a succession of impressions
(tactual and auditory are most favorable) which vary regularly
in objective intensity. We desire to understand the nature,
and the source of the pleasing quality, of this phenomenon.

It is only by a complete psychological description, however,
even a physiological explanation, that we can hope to fathom
the tremendous significance of rhythm in music and poetry.
Those treatments which expose its development in the dance and
song really beg the question; they assume the very fact for
which we have to find the ground, namely, the natural impulse
to rhythm. Even those theories which explain it as a helpful
social phenomenon, as regulating work, etc., fail to account
for its peculiar psychological character--that compelling,
intimate force, the "Zwang" of which Nietszche speaks, which
we all feel, and which makes it helpful. This compelling
quality of rhythm would lead us to look behind the sociological
influences, for the explanation in some fundamental condition
of consciousness, some "demand" of the organism. For this
reason we must find superficial the views which connect rhythm