A man once hurt his leg. He had to walk with a crutch. This crutch was very useful to him, both for walking and many other things.

He taught all his family to use crutches and they became part of normal life. It was part of everyone's ambition to have a crutch. Some were made of ivory, others adorned with gold. Schools were opened to train people in their use, university chairs endowed to deal with the higher aspects of this science.

A few, a very few people, started to walk without crutches. This was considered scandalous, absurd. Besides, there were so many uses for crutches.

Some replied, and were punished. They tried to show that a crutch would be used sometimes, when needed; or that many of the other uses to which a crutch was put could be supplied in other ways.

Few listened.

In order to overcome the prejudices, some of the people who could walk without support began to behave in a totally different way from established society.

Still they remained few.

When it was found that, having used crutches for so many generations, few people could in fact walk without crutches, the majority 'proved' that they were necessary. "Here," they said, "here is a man - try to make him walk without a crutch. See? - he cannot!"

"But we are walking without crutches," the ordinary walkers reminded them.

"This is not true; merely a fancy of your own," said the cripples, because by that time they were become blind as well - blind because they would not see.