Simply stated, the basic principle of evolution is: What is used develops. Birds fly not because they have wings; they have wings because they fly.
The best example I know is Benjamin Rossow, a boy who was born without a brain. All he was given at birth was the cerebral cortex, a brain stem, to guide his actions.
The potential quality of Ben's life and the possibilities of his birth were judged so limited, the learned men of medicine who brought him into the world concluded there was no point to his life. Besides, they said, it was unlikely he would live more than year under the best of circumstances.
Ben surprised them. When I met him a dozen years later, he was doing things said to be impossible when he was born. Benjamin tracked his mother with his eyes, responded to her embrace, and laughed when she laughed. He not only knew who she was, he knew where she was all the time.
Now when I think of Ben I remember a pure person. He was a boy who knew nothing of prejudice, never learned to hate, and never even dreamed of harming another person. He never knew doubt and had no fear. As a result, while most of us only use a fraction of our potential, he was performing at least at 150 percent of what was said to be his capacity.
All Ben knew was love -- the love he was given and the love he gave -- and that love enabled the child who it was said would never make a difference to change the Baby Doe laws in three states.
His message is simple: The deepest defeat we can suffer is the distance between where we are and what we are capable of being. The things we regret most in life are not the things we could never do, but rather the things we might have done had we only tried.
It is not our impossibilities that fill us with despair, but the possibilities we have failed to actualize. The greatest defeat is the distance between what we are and what we can be.