n this ground glass, so rays of light
coming from any object pass first through the small opening of the eye,
to the retina, where the picture is inverted just the same as upon the
ground glass. When this picture is thrown upon the rear wall of the eye,
which is called the retina, the seeing nerve, which is called the optic
nerve and is connected with the eye, conveys the impression to the
brain, and the result is what we call seeing.

[Illustration: The Human Eye.]

What I have told you is correct, and can easily be proven by a simple
experiment with the eye of some animal. If you take the eye of a dead
rabbit, and cleanse the back portion of it from the fat and muscles and
then hold a candle in front of it, you can see the image of the candle
formed upon the retina. If you take the eye of an ox and carefully pare
off from the back portion, so as to leave it very thin, and place the
eye in front of (or against) a small hole made in a box; then cover your
head to shut out the light you will see through the box the picture of
any object which is directly in front of this eye of the ox. In both
instances they will be in the inverted form. This experiment would fully
demonstrate to you that the camera is only an imitation, and a very poor
one too, of the human eye.

Now when pictures are taken by means of the camera, the negative can not
be exposed to the light, but must be taken into a dark room, and be
carefully developed by the use of necessary chemicals or liquids. Then
specially prepared paper must be used for printing the photographs. This
paper must also be kept in the dark until it has been thoroughly washed
and cleansed. But, with the pictures which are taken upon the retina of
the eye, no such delay and labor is necessary before you can look at
them. The moment the eye is turned in any direction, instantly the
picture is photographed upon the retina of the eye, and then stamped
indelibly upon the memory and becomes a part of ourselves.

There is no cost for chemicals, no delay in adjusting the instrument
with which the picture is taken, no necessity for carrying around a
large camera.

The camera has many disadvantages which are not found in the human eye.
The camera must be adjusted to objects near or far, and different
cameras have to be used for pictures of different sizes and for
different classes of pictures. These cameras are costly to purchase, a
great deal of time is consumed in securing a few pictur