Before we can talk intelligently about the problems of blindness or the potentialities of blind people, we must have a workable definition of blindness. Most of us are likely familiar with the generally accepted legal definition: visual acuity of not greater than 20/200 in the better eye with correction or a field not subtending an angle greater than 20 degrees. But this is not really a satisfactory definition. It is, rather, a way of recognizing in medical and measurable terms something which must be defined not medically or physically but functionally. Putting to one side for a moment the medical terminology, what is blindness? Once I asked a group of high school students this question, and one of them replied--apparently believing that he was making a rather obvious statement--that a person is blind if he "can't see." When the laughter subsided, I asked the student if he really meant what he said. He replied that he did. I then asked him whether he would consider a person blind who could see light but who could not see objects: a person who would bump into things unless he used a cane, a dog, or some other travel aid and who would, if he depended solely on the use of his eyesight, walk directly into a telephone pole or fire plug. After some little hesitation the student said that he would consider such a person to be blind. I agreed with him and then went on to point out the obvious--that he literally did not mean that the definition of blindness was to be unable to see. I next told this student of a man I had known who had "normal" (20/20) visual acuity in both eyes but who had such an extreme case of sensitivity to light that he literally could not keep his eyes open at all. The slightest amount of light caused such excruciating pain that the only way he could open his eyes was by prying them open with his fingers. Nevertheless, this person, despite the excruciating pain he felt while doing it, could read the eye chart without difficulty. The readings showed that he had "normal sight." This individual applied to the local governmental agency for assistance and was duly examined by their ophthalmologist. The question I put to the student was this: "If you had been the ophthalmologist, would you have granted the aid or not?" His answer was, "Yes." "Remember," I told him, "under the law you are forbidden to give aid to any person who is not actually blind. Would you still have granted the assistance?" The student said that he would. Again, I agreed with him, but I pointed out that, far from his first facetious statement, what he was saying was this: It is possible for one to have "perfect sight" and still in the physical, literal sense of the word be blind. I then put a final question to the student. I asked him whether if a sighted person were put into a vault which was absolutely dark so that he could see nothing whatever, it would be accurate to refer to that sighted person as a blind man. After some hesitation and equivocation the student said, "No." For a third time I agreed with him. Then I asked him to examine what we had established: 1. To be blind does not mean that one cannot see. (Here again I must interrupt to say that I am not speaking in spiritual or figurative terms but in the most literal sense of the word.) 2. It is possible for an individual to have "perfect sight" and yet be physically and literally blind. 3. It is possible for an individual not to be able to see at all and still be a sighted person. What, then, in light of these seeming contradictions is the definition of blindness? In my way of thinking it is this: One is blind to the extent that he must devise alternative techniques to do efficiently those things which he would do with sight if he had normal vision. An individual may properly be said to be "blind" or a "blind person" when he has to devise so many alternative techniques--that is, if he is to function efficiently--that his pattern of daily living is substantially altered. It will be observed that I say alternative not substitute techniques, for the word substitute connotes inferiority, and the alternative techniques employed by the blind person need not be inferior to visual techniques. In fact, some of them are superior. The usually accepted legal definition of blindness already given (that is, visual acuity of less than 20/200 with correction or a field of less than 20 degrees) is simply one medical way of measuring and recognizing that anyone with better vision than the amount mentioned in the definition will (although he may have to devise some alternative techniques) likely not have to devise so many such techniques as to alter substantially his patterns of daily living. On the other hand, anyone with less vision than that mentioned in the legal definition will usually (I emphasize the word usually, for such is not always the case) need to devise so many such alternative techniques as to alter quite substantially his patterns of daily living. It may be of some interest to apply this standard to the three cases already discussed: First, what of the person who has light perception but sees little or nothing else? In at least one situation he can function as a sighted person. If, before going to bed, he wishes to know whether the lights are out in his home, he can simply walk through the house and "see." If he did not have light perception, he would have to use some alternative technique: touch the bulb, tell by the position of the switch, have some sighted person give him the information, or devise some other method. However, this person is still quite properly referred to as a blind person. This one visual technique which he uses is such a small part of his overall pattern of daily living as to be negligible in the total picture. The patterns of his daily living are substantially altered. In the main he employs alternative techniques to do those things which he would do with sight if he had normal vision--that is, he does if he functions efficiently. Next, let us consider the person who has normal visual acuity but cannot hold his eyes open because of his sensitivity to light. He must devise alternative techniques to do anything which he would do with sight if he had normal vision. He is quite properly considered to be a "blind person." Finally, what of the sighted person who is put into a vault which has no light? Even though he can see nothing at all, he is still quite properly considered to be a "sighted person." He uses the same techniques that any other sighted person would use in a similar situation. There are no visual techniques which can be used in such circumstances. In fact, if a blind person found himself in such a situation, he might very well have a variety of techniques to use. I repeat that, in my opinion, blindness can best be defined not physically or medically but functionally or sociologically. The alternative techniques which must be learned are the same for those born blind as for those who become blind as adults. They are quite similar (or should be) for those who are totally blind or nearly so and those who are "partially sighted" and yet are blind in the terms of the usually accepted legal definition. In other words, I believe that the complex distinctions which are often made between those who are totally blind, between those who have been blind from childhood and those who have become blind as adults are largely meaningless. In fact, they are often harmful since they place the wrong emphasis on blindness and its problems. Perhaps the greatest danger in the field of work for the blind today is the tendency to be hypnotized by jargon.