That the sapphire should have been regarded as especially valuable for the cure of eye diseases serves to illustrate the wide-reaching and persistent influence of Egyptian thought, and the curious transformations through which an originally reasonable idea may pass in the course of time. We have already noted that the sapphire of the ancients was our lapis-lazuli, and in the Ebers Papyrus lapis-lazuli is given as one of the ingredients of an eye-wash. This ingredient is believed to have originally been the oxide of copper sometimes called lapis Armenus, a material possessing marked astringent properties, and which might be used to advantage in certain morbid conditions of the eye. Lapis-lazuli, another blue stone, was later substituted because of its greater intrinsic value, its similarity of color rendering it equally efficacious according to primitive ideas on this subject. When, however, in medieval times, the name sapphire came to signify the blue corundum gem known to us by this designation, the special curative virtues of the lapis-lazuli were transferred to this still more valuable stone. The proper method of applying a sapphire to cure plague boils is given at some length by Van Helmont. A gem of a fine, deep color was to be selected and rubbed gently and slowly around the pestilential tumor. During and immediately after this operation, the patient would feel but little alleviation; but a good while after the removal of the stone, favorable symptoms would appear, provided the malady were not too far advanced. This Van Helmont attributes to a magnetic force in the sapphire by means of which the absent gem continued to extract “the pestilential virulency and contagious poyson from the infected part.”[505] Topaz The use of a topaz to cure dimness of vision is strongly recommended by St. Hildegard. To attain the desired end the stone was to be placed in wine and left there for three days and three nights. When retiring to sleep, the patient should rub his eyes with the moistened topaz, so that this moisture lightly touched the eyeball. After the stone had been removed, the wine could be used for five days.[506] A Roman physician of the fifteenth century was reputed to have wrought many wonderful cures of those stricken by the plague, through touching the plague sores with a topaz which had belonged to two popes, Clement VI and Gregory II. The fact that this particular topaz had been in the hands of two supreme pontiffs must have added much to the faith reposed in the curative powers of the stone by those upon whom it was used, and this faith may really have helped to hasten their recovery.[507] Bloodstone