There was once a man who had a remarkable pair of spectacles, rather like Reactolite Rapides except that, like a mood ring, they changed their colour according to his feelings of the moment. When sad, all the world would appear in the colours of sadness; when fearful, in the colours of fear; when angry, in the colours of anger; when contented, in the colours of joy.
He could make no sense of these varied colourings which would not stay still. He had no success in trying to understand why the world kept changing in this way. He suspected that his spectacles might be the cause of the mystery, but every time he took them off to look at them they were, of course, completely clear.