And yet the distance in which the people move is not the distance of our real space, such as the theater shows, and the persons themselves are not flesh and blood.

It is a unique inner experience, which is characteristic of the perception of the photoplays.

_We have reality with all its true dimensions; and yet it keeps the fleeting, passing surface suggestion without true depth and fullness, as different from a mere picture as from a mere stage performance._ It brings our mind into a peculiar complex state; and we shall see that this plays a not unimportant part in the mental make-up of the whole photoplay.
While the problem of depth in the film picture is easily ignored, the problem of movement forces itself on every spectator.

It seems as if here the really essential trait of the film performance is to be found, and that the explanation of the motion in the pictures is the chief task which the psychologist must meet.

We know that any single picture which the film of the photographer has fixed is immovable.