Sylvester Rosa Koehler

“ And yet, as I have said before, there are people who live in such a world continually, and must continue to live in it to their days' end. Fortunately, however, the instances of people who are totally color-blind—that is to say, who are absolutely incapable of experiencing the sensation of color—are extremely rare; and, to the few people so afflicted, the deprivation is not so great as it would seem to be to us, since, having never known the poetry of color, they do not feel the want of it. ”

“ Even to those, however, who are fully alive to the charm of color, the latter is so much a matter of fact that they take its presence for granted, and accept as a foregone conclusion that it can never be otherwise. The question, How would the world look without color? ”

“ Even the bright red of some flowers may only present itself to such persons as a lighter shade of the color of the leaves, while yellow and blue are perceived by them quite as distinctly as by persons of normal vision. To them, therefore, the world must bear a resemblance in color to some of the old pottery which is decorated in blue, yellow, and black, on a whitish ground. There are other varieties of defective color-vision, all of which may be generally described as an inability to perceive certain colors, while the perception of certain other colors is normal. ”

“ In the case of total color-blindness, we need only to assume that the nerve-fibers are in an abnormal condition, so that each set, instead of responding to only one sensation, responds equally to all. The result must necessarily be a total absence of color in the impressions received through the eye. In the case of a red-blind person, the nerves which ought to respond to red may either be paralyzed or they may be wanting altogether, and all other defects in color-vision may be explained upon the same principle. ”

“ But the consequences that may possibly arise from it are of a far more serious nature when the safety of a large number of human beings is dependent on the color-vision of a single individual. This is the case with railroad operatives, who must be able without fail to tell one signal from another; and, as of late years the conviction has gained ground that color-blindness is far more common than it was formerly supposed to be, the railroad companies are warned more emphatically from year to year by scientific men to see to the eyes of their employees. ”

“ A person thus afflicted can detect no difference between the ripe cherry on the tree and the leaves by which it is surrounded, or between the strawberry and the stems and leaves of the plant on which it grows. ”