For several days the thon and his assistant studied the library itself, the files, the monastery’s records apart from the Memorabilia-as if by determining the validity of the oyster, they might establish the possibility of the pearl. Brother Kornhoer discovered the thon’s assistant on his knees in the entrance of the refectory, and for a moment he entertained the impression that the fellow was performing some special devotion before the image of Mary above the door, but a rattle of tools put an end to the illusion. The assistant laid a carpenter’s level across the entranceway and measured the concave depression worn in the floor stones by centuries of monastic sandals.