slow ones are more voluptuous and allied to the richer varieties of passive sensation. In following straight lines, and in tracing the outlines of objects, the eye has, it is obvious, a choice out of an indefinite number of velocities of movement. It is probable, for the reason just given, that under these circumstances it usually prefers a slow to an excitingly rapid species of movement.[1]
For a similar reason those directions of ocular movement which answer to easy and habitual muscular action, have more of a pleasurable character than those which soon approach the threshold of fatigue. Thus, an horizontal line is, as a rule, in itself, and apart from any extraneous consideration, more enjoyable, because more restful, than a vertical. Let the reader compare the feelings he has in looking at architecture, in which the vertical direction predominates, and at the approximately horizontal lines of a flat landscape. A somewhat analogous difference exists between movements of the two eyes with strongly converging and with parallel axes. The sweet repose of distance arises in part from this comparatively relaxed form of muscular activity.
So much as to the pleasure of single ocular movement. Let us now see how a pleasant succession of movements is to be secured. The conditions of agreeable sequence of movement seem to be the combination of the refreshing and stimulating element of change with an element of smoothness or ease of transition. Change of movement is, of course, necessitated by the universal condition of mental life, and variety is the very essence of all æsthetic experience, all monotonous feeling being wearisome. On the other hand, a chain of varied movements may be smooth and agreeable, or jerky and harsh, and this difference is related to the innate mechanical conditions of movement, and to the effects of habit.
Change of movement may most easily be secured by a variation either of velocity or of direction.[2] One and the same movement may vary in velocity, as in watching the ascent or descent of a projectile thrown up vertically. So different movements may present a difference of velocity as in the sequences of a ballet. Such contrasts plainly answer to the most favorable mode of expending motor energy. Again, our movement may be followed by another of different direction; that is to say, one that involves the action of fresh muscular elements, or a change in the relative amounts of action of two or more combining muscles. All complicated movements of objects and all arrangements of lines in the figures of bodies supply such variation in abundance.
So much as to change of element. Let us now pass to the other condition of agreeable sequence, namely, smoothness. The first and
