the foreground and the landscape far away.

_Nevertheless we are never deceived; we are fully conscious of the
depth, and yet we do not take it for real depth._ Too much stands in the
way. Some unfavorable conditions are still deficiencies of the
technique; for instance, the camera picture in some respects exaggerates
the distances. If we see through the open door of the rear wall into one
or two other rooms, they appear like a distant corridor. Moreover we
have ideal conditions for vision in the right perspective only when we
sit in front of the screen at a definite distance. We ought to sit
where we see the objects in the picture at the same angle at which the
camera photographed the originals. If we are too near or too far or too
much to one side, we perceive the plastic scene from a viewpoint which
would demand an entirely different perspective than that which the
camera fixated. In motionless pictures this is less disturbing; in
moving pictures every new movement to or from the background must remind
us of the apparent distortion. Moreover, the size and the frame and the
whole setting strongly remind us of the unreality of the perceived
space. But the chief point remains that we see the whole picture with
both eyes and not with only one, and that we are constantly reminded of
the flatness of the picture because the two eyes receive identical
impressions. And we may add an argument nearly related to it, namely,
that the screen as such is an object of our perception and demands an
adaptation of the eye and an independent localization. We are drawn into
this conflict of perception even when we look into a mirror. If we stand
three feet from a large mirror on the wall, we see our reflection three
feet from our eyes in the plate glass and we see it at the same time six
feet from our eye behind the glass. Both localizations take hold of our
mind and produce a peculiar interference. We all have learned to ignore
it, but characteristic illusions remain which indicate the reality of
this doubleness.

In the case of the picture on the screen this conflict is much stronger.
_We certainly see the depth, and yet we cannot accept it._ There is too
much which inhibits belief and interferes with the interpretation of the
people and landscape before us as truly plastic. They are surely not
simply pictures. The persons can move toward us and away from us, and
the river flows into a distant valley. And yet the distance in which the