The natural tendency might be to lay the chief stress on the fact that those people in the photoplay do not stand before us in flesh and blood.

The essential point is rather that we are conscious of the flatness of the picture.

If we were to see the actors of the stage in a mirror, it would also be a reflected image which we perceive.

We should not really have the actors themselves in our straight line of vision; and yet this image would appear to us equivalent to the actors themselves, because it would contain all the depth of the real stage.

The film picture is such a reflected rendering of the actors.