make such an experiment. If he investigates the results of scientific tests in psychological laboratories he will learn that under certain conditions the normal spectator unconsciously creates rhythm in what he sees. It has been shown, for example, that a person looking at a small light which is flashed on and off at intervals has a tendency to make rhythmic groupings of those flashes, by overestimating or underestimating the lengths of the intervals. In other words, if you give the beholder's imagination a chance to function, it will indulge in rhythmic play. We believe that if a cinema composer could thus produce rhythm by illusion, as well as by actual presentation, his achievement would be epoch-making in the movies.
Movement, movement through rich variety, movement accomplished with the utmost ease—that is the essence of what we have chosen to call the play of pictorial motions. That play, as we have seen in the illustrations given, involves every kind of pictorial motion, whether of spot, or line, or pattern, or texture, or tone; and every property or phase, whether of direction, or rate, or duration; and every circumstance, whether in relation to other motions near or remote, simultaneous, or successive, or in relation to fixed elements of the picture. Any two or three of these things may be treated as a separate problem, but it is in the orchestration of all of them together that the director may achieve the dominant, distinctive rhythm of his photoplay. If he does not aspire to such achievement he is unworthy of his profession. If he evades his problems because they are difficult he is robbing his trust. If he declares that the world that loves movies does not crave beauty on the screen,
