Camera.
To illustrate my thought, I have to-day brought a camera. Sometimes such a camera as this is called a Kodak or Snap-shot. As the finest telescopes have been modeled after the human eye, so the camera is only a very imperfect imitation of the human eye. As the spy-glass and telescope have lenses, so does this camera have a lens, which you see here in the front. Just back of this lens is the dark chamber in the camera, and back of it is a ground glass, as you will see here. Now whatever is directly in front of the camera is shown on the ground glass, as you will observe, but in an inverted or up-side-down position. So the eye has its various parts, and as the rays of light pass through this lens and reflect the picture on 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.
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 pictures, they are always attended with expense; and when pictures are to be removed from one place to another, the owner is subjected to much trouble and annoyance. Then, the camera also does not give us the colors of the different objects which are before it. That is the reason why, in the beginning, I spoke of these millionaires purchasing such costly paintings, because in the paintings different colors are represented.