Indeed, we can go further: A man born blind might become a physicist and specialize in the physics of color; this would be a somewhat peculiar choice, no doubt, but it would be a possible one. Such a man would never have seen any colors, and therefore he would have no color-images. But he might well know more facts about colors than you or I: he could tell us more about the light-waves and other physical properties of colored objects, and more about the physical conditions under which colors are seen, than most people can. He would in fact be able to tell us what the color of every object is; not by looking at it as we do, but by reading in Braille the pointer readings on instruments that record the wave-lengths of light emanating from the objects. He would be able to impart to us a great deal of knowledge about color and colored objects; and how could he do this if he did not have the concept of color? If he did not possess this, how could he know what he was talking about? Of course, he could correctly identify colors only as long as the correlation held between the seen color and the wave-lengths of light; if this correlation were no longer to hold, he would start making mistakes in color identification because he could not see the colors but had only the indirect evidence of the instruments recording light-waves. Still, must we not admit that he has the concept of color, even though he is unable to experience any color-images? How could he use the word, and even impart to us new knowledge that presupposes knowledge of what the word means, unless he had the concept?