The testimony of John of Salisbury (1120?-1180) shows that in the twelfth century, in England, divination by means of the arts of the _specularii_ was often practised. The prelate writes that when a boy, he himself and a companion a few years older received instruction from a priest who was addicted to the use of these magic arts. This priest used to polish the finger-nails of the boys with a consecrated oil or ointment, and then direct them to look upon the polished surface until some figure or form should appear. Sometimes the smooth, polished surface of a basin was used. John of Salisbury regarded it as a mark of divine favor that he himself saw nothing upon the smooth and lustrous surface, but he states that his companion observed certain vague and shadowy forms. Certain names pronounced by the priest on these occasions terrified the boy, for he believed them to be the names of evil spirits; indeed, such was his reluctance to participate in the unholy rites that his presence was believed to interfere with the production of the phenomena.[279] In another part of his “Policraticus,” John of Salisbury states that the specularii claimed that their gift of seeing visions on polished surfaces was never used to injure any one, but was often useful in the detection of theft and in counteracting magic spells.[280] Under the comprehensive chapter heading: “How to conjure the crystal so that all things may be seen in it,” Paracelsus (1493-1541) declares that “to conjure” means nothing more than “to observe anything rightly, to learn and to understand what it is.” The crystal was of the nature of the air, and hence all things movable and immovable that could be seen in the air could also be seen in the crystal or _speculum_.[281] Paracelsus showed keen insight, and his conclusions are excellent. One might add, however, that it is a fact that these are images condensed in the double convex lens, forming as it were, an internal crystal sphere. These images are reversed, distorted and twisted, and when they become visible to one who is expecting strange things, they form mental impressions which it is often very difficult to erase. Many crystal gazers are frequently very highly wrought, nervous and susceptible, and other influences uniting with the impressions produced, may give the brain for a time the power to evolve kaleidoscopic effects. Directions for the use of an Erdenspiegel, or “earth-mirror,” are given in an old German manuscript written in 1658 by a Capuchin priest.[282] The mirror is to be set about two inches above a board, and the questions to be answered are to be placed beneath it. The scryer is recommended to place three grains of salt upon his tongue, whereupon he is to repeat a prayer and cross himself. He now takes the mirror in his hand and breathes upon it three times, repeating the words, “In the name of the Father, of the Son, and of the Holy Spirit. Amen.”