The landscape is taken from two different points of view, once from the right and once from the left.

As soon as these two views are put into the stereoscope the right eye sees through the prism only the view from the right, the left eye only the view from the left.

We know very well that only two flat pictures are before us; yet we cannot help seeing the landscape in strongly plastic forms.

The two different views are combined in one presentation of the landscape in which the distant objects appear much further away from us than the foreground.

We feel immediately the depth of things.