The defiance of biological destiny has been repeatedly demonstrated. After suffering injury to one part of the brain, for instance, causes a different part to develop more fully. One faculty compensates for another. So my blind piano tuner has a keen sense of hearing, and someone who is paralyzed can accomplish great things using his mind. Furthermore, how should we measure achievement? Someone in a race who starts out at a disadvantage may come in second, but he has emerged as the better runner. (p. 83-85)
In all of these cases people have defied nature by compensating and by continuing to strive for their goals despite the barriers. Who hasn’t been inspired by the story of Hellen Keller and Anne Sullivan? People like these have been able to achieve great things because they came to a place of inner acceptance of what they lost, and maintained firm belief in what they still had.
Whether it’s easier to come to this acceptance when the handicap is a physical one rather than a psychological one is not clear to me. I imagine it’s very individual, and anything physical has a psychological component as well. It’s funny how people develop most fully only when they’re challenged to do so.