imitate or replace anything, but is in itself an art as different from that of the theater as the painter's art is different from that of the sculptor? And may it not be high time, in the interest of theory and of practice, to examine the esthetic conditions which would give independent rights to the new art? If this is really the situation, it must be a truly fascinating problem, as it would give the chance to watch the art in its first unfolding. A new esthetic cocoon is broken; where will the butterfly's wings carry him? We have at last reached the real problem of this little book. We want to study the right of the photoplay, hitherto ignored by esthetics, to be classed as an art in itself under entirely new mental life conditions. What we need for this study is evidently, first, an insight into the means by which the moving pictures impress us and appeal to us. Not the physical means and technical devices are in question, but the mental means. What psychological factors are involved when we watch the happenings on the screen? But secondly, we must ask what characterizes the independence of an art, what constitutes the conditions under which the works of a special art stand. The first inquiry is psychological, the second esthetic; the two belong intimately together. Hence we turn first to the psychological aspect of the moving pictures and later to the artistic one. PART I THE PSYCHOLOGY OF THE PHOTOPLAY CHAPTER III[1] DEPTH AND MOVEMENT [1] Readers who have no technical interest in physiological psychology may omit Chapter III and turn directly to Chapter IV on Attention.