l world, and the movements of
the persons or of the animals or even of the lifeless things, like the
streaming of the water in the brook or the movements of the leaves in
the wind, strongly maintain our immediate impression of depth. Many
secondary features characteristic of the motion picture may help. For
instance, by a well-known optical illusion the feeling of depth is
strengthened if the foreground is at rest and the background moving.
Thus the ship passing in front of the motionless background of the
harbor by no means suggests depth to the same degree as the picture
taken on the gliding ship itself so that the ship appears to be at rest
and the harbor itself passing by.

The depth effect is so undeniable that some minds are struck by it as
the chief power in the impressions from the screen. Vachel Lindsay, the
poet, feels the plastic character of the persons in the foreground so
fully that he interprets those plays with much individual action as a
kind of sculpture in motion. He says: "The little far off people on the
oldfashioned speaking stage do not appeal to the plastic sense in this
way. They are by comparison mere bits of pasteboard with sweet voices,
while on the other hand the photoplay foreground is full of dumb giants.
The bodies of these giants are in high sculptural relief." Others have
emphasized that this strong feeling of depth touches them most when
persons in the foreground stand with a far distant landscape as
background--much more than when they are seen in a room. Psychologically
this is not surprising either. If the scene were a real room, every
detail in it would appear differently to the two eyes. In the room on
the screen both eyes receive the same impression, and the result is that
the consciousness of depth is inhibited. But when a far distant
landscape is the only background, the impression from the picture and
life is indeed the same. The trees or mountains which are several
hundred feet distant from the eye give to both eyes exactly the same
impression, inasmuch as the small difference of position between the two
eyeballs has no influence compared with the distance of the objects from
our face. We would see the mountains with both eyes alike in reality,
and therefore we feel unhampered in our subjective interpretation of far
distant vision when the screen offers exactly the same picture of the
mountains to our two eyes. Hence in such cases we believe that we see
the persons really in