A great many cases of defective eyesight, so called, are in reality defective brain. The mechanism of the eye may be perfect, the retina and the optic nerve may faithfully perform their duties, but if the brain behind the eye be defective, the comprehension of the object or some of its properties is lost to the intelligence of the individual. Some people are "color blind." Their eyes are good enough, but they don't see colors; they comprehend no difference in the shades of different colored objects exhibited to the view. At the same time they fully comprehend the size, form, distance, etc., of the object. An examination discloses the fact that they are deficient in a portion of the brain just behind the middle of the eyebrow. Give such a man every material and brush of the painter and request him to paint a landscape and the result will be a daub. He has no sense of colors, he has no fitness for that kind of work. At the same time he may be entirely capable of a very creditable performance in drawing a picture with a pencil in white and black because that does not involve his weakness. This particular element of sense may, like all others, be only partially defective, but an examination by a competent phrenologist will disclose its exact state, whatever it may be. I once examined a man and remarked to him that he was thoroughly endowed with the qualities essential to a good locomotive engineer, except that the organ of color was slightly deficient. I remarked, "You will never experience the slightest inconvenience in distinguishing switch-lights and signals when you are in good health and sober, but a slight indigestion, or a glass of liquor, decreasing the power of your brain, would render your vision of colors unreliable and might cause a wreck, hence I advise you to keep out of the business." The man was a railroad engineer, and admitted that he could generally distinguish colors without difficulty, but that his color sense was lost, under the conditions I described.