91. It often happens that a line repeated in different attitudes
gives us the sense of movement. It does this when the grouping of the
repetitions suggests instability. The movement is rhythmical when it
exhibits a regularity of changes in the attitudes and in the intervals
of the changes.
[Illustration: Fig. 118]
In this case we have a movement to the right, but no Rhythm, the
intervals being irregular.
[Illustration: Fig. 119]
In this case the changes of attitude and the intervals of the changes
being regular, the movement becomes rhythmical. The direction of the
rhythm is clearly down-to-the-right.
92. In the repetition of any line we have a Harmony, due to the
repetition. If the line is repeated in the same attitude, we have a
Harmony of Attitudes. If it is repeated in the same intervals, we have
a Harmony of Intervals. We have Harmony, also, in the repetition of any
relation of attitudes or of intervals.
We have not yet considered the arrangement or composition of two or
more lines of different measures and of different shapes.