4. By the Order of Rhythm I mean changes of sensation; changes in
muscular impressions as we feel them, in sounds as we hear them, in
sights as we see them; changes in objects, people, or things as we know
them and think of them, changes which induce the feeling or idea of
movement, either in the duration of Time or in the extension of Space;
provided that the changes take place at regular and marked intervals of
time or in regular and marked measures of space. By regular intervals
and measures I mean equal or lawfully varying intervals and measures. I
do not mean, by Rhythm, changes simply, inducing the sense or idea of
movement: I mean, by Rhythm, a regularity of changes in a regularity of
measures, with the effect of movement upon our minds.
Rhythms in Time differ from Rhythms in Space, inasmuch as the movement
in Time is in one direction, inevitably. It lies in the duration and
passing of time, from which nothing escapes. The movement in space,
on the contrary, may be in any one of many possible directions. A
movement in different directions, particularly in contrary directions,
amounts to a negation of movement. In any space-rhythm, therefore,
the direction in which the rhythm leads us, the direction in which we
follow it, must be unmistakable.
5. Of these three principles of Order, the first and foremost, the most
far-reaching and comprehensive, is the principle of Harmony. We have
Harmony in all balances, and we have it also in all rhythms. It is,
therefore, undesirable to think of the three principles as coördinate.
It will be better to think of the principle of Harmony first, and then
of two other principles, those of Balance and of Rhythm, as lying
within the range of Harmony but not coextensive with it. We might
express the idea in a logical diagram.
[Illustration: Fig. 1]
Within the field of Harmony we have two distinct modes of Order—Balance
and Rhythm; but we have Harmony beyond the range of Balance and beyond
the range of Rhythm.
In cases where rhythms, corresponding in character and in direction
of movement, are set side by side, one on the right, the other on the
left, of a vertical axis, so that they balance, one against the other,
and the vertical axis of the balance is the line of the movement,
we have the union of all three principles. This idea, also, may be
expressed in a logical diagram.
[Illustration: Fig. 2]
Examples of this union of the three principles of Order will be given
farther on.