"Well, it was of Roman workmanship, of a stone that with the centuries had not blackened, but had become white and luminous. The thicket had grown up about it and concealed it, and in the Middle Ages the followers of a very old tradition had known how to use it for their own purposes. In fact it had been incorporated into the monstrous mythology of the Sabbath. You will have noted that those to whom a sight of that shining whiteness had been vouchsafed by chance, or rather, perhaps, by apparent chance, were required to blindfold themselves on their second approach. That is very significant."