The treatise known under the title “Cyrianides” was, as we have noted, a product of the Alexandrian school. It was asserted to be the work of Hermes Trismegistus, the name given by the Greeks to the Egyptian god Thoth. Here we have a specimen of the species of magic known as litteromancy, or divination by means of the letters of the alphabet, since a stone, a bird, a plant, and a fish, each beginning with the same letter and signifying the four elements, are given for each of the twenty-four letters of the Greek alphabet. These four objects were to be grouped together to form a talisman, the bird being usually engraved on the stone, while a portion of the fish and of the plant was placed in the bezel of the ring in which the stone was to be set.[8] Another, almost contemporary work, is the exceedingly curious and interesting treatise by St. Epiphanius, Bishop of Constantia, on the twelve gems on the “Breastplate of Judgment” of the high priest (Ex., xxviii, 15-21). This unique production is in the form of a letter addressed to Diodorus, Bishop of Tyre, and it is peculiarly valuable as the first of a long series of attempts to elucidate the question as to the identity of the twelve stones. The special virtues of each stone are also given, and this treatise may be regarded as the prototype of all the Christian writings on the symbolism of stones. A most interesting medieval treatise on the virtues of precious stones forms part of the _De rerum natura_ of Thomas de Cantimpré (1201-1270), who was a pupil of Albertus Magnus and composed his work between 1230 and 1244. The Latin text has never been printed, but the book was translated into German by Konrad von Megenberg about 1350. Strange to say, the translator did not know the name of the writer and supposed when he began to translate the book that it was by Albertus Magnus. In many cases Thomas de Cantimpré merely copies the statements of older authors, but occasionally he gives us new material, or at least a new version of his originals. [Illustration: Title page of one of the earliest treatises on precious stones published in England.]