Fig. 42
There is no movement in this series of repetitions. There is consequently no Rhythm. Disregarding the habit of reading to the right, which induces the eye to move in that direction, it is as easy to move toward the left as toward the right. It requires more than repetitions at equal intervals to produce the feeling of Rhythm. There must be movement, and the movement must have a definite direction.
42. Second. The substitution at each point of a symmetrical group at equal intervals, as before, but with a progressive change of scale, will give us Rhythm. The movement will be due to the gradual crowding together of attractions at one end of the series.
Fig. 43
In this case we have the repetition of a symmetrical relation of positions at equal intervals with a gradation of scale in the repetitions. The result is a Rhythm, in which the movement is from left to right, owing to the greater crowding together of attractions at the right end of the series. The feeling of Rhythm is no doubt somewhat enhanced by our habit of reading to the right, which facilitates the movement of the eye in that direction.
43. Third. The substitution of an unstable group at each point of the sequence, the repetitions being at equal intervals, gives us a Rhythm, due simply to the movement of the group itself, which is unstable.
Fig. 44
Taking the relation of positions given in [Fig. 36] and repeating it at equal intervals, it will be observed that the falling-to-the-right movement, which is the result of instability, is conveyed to the whole series of repetitions. To make it perfectly clear that the movement of this Rhythm is due to the suggestion of movement in the relation of positions which is repeated, I will ask the reader to compare it with the repetition of a symmetrical group in [Fig. 42]. There is no movement in that case, therefore no Rhythm.