There is a legend of the Middle Ages that is very instructive. It seems that a citizen was arrested by one of the barons and shut up in a dungeon beneath his castle. He was taken down dark stairs, down, down, down, by a ferocious-looking jailer who carried a great key a foot long. The door of the cell was opened, and he was thrust into a dark hole. The door shut with a bang, and there he was.

He lay in that dark dungeon for twenty years. Each day the jailer would come, the big door would be opened with a great creaking and groaning, a pitcher of water and a loaf of bread would be thrust in and the door closed again.

After twenty years the prisoner decided that he could not stand it any longer. He wanted to die but he did not want to commit suicide, so he decided that the next day when the jailer came he would attack him. The jailer would then kill him in self-defense, and thus his misery would be at an end. He thought he would examine the door carefully so as to be ready for tomorrow and, going over, he caught the handle and turned it. To his amazement the door opened, and upon investigation he found that there was no lock upon it and never had been, and that for those twenty years he had not been locked in ... except in belief.

At any time in that period he could have opened the door if only he had known it. He thought it was locked, but it was not. He groped along the corridor and felt his way upstairs. At the top of the stairs two soldiers were chatting, and they made no attempt to stop him. He crossed the great yard without attracting attention. There was an armed guard on the drawbridge at the great gate, but they paid no attention to him, and he walked out a free man.

He went home unmolested and lived happily ever after. He could have done this any time through those long years since his arrest if he had known enough, but he did not. He was a captive, not of stone and iron, but of false belief. He was not locked in; he only thought he was. Of course this is only a legend, but it is an extremely instructive one.