The _lapis nephriticus_ (jade) was held to be a remedy for œdematous affections of the feet. As this stone was so highly in favor in Europe for a century or two after it had first been brought from America by the Spaniards, many were of the opinion that it should be constantly worn to exert its full curative power. There were some, however, who argued that with this as with other remedies, constant and unremitting use weakened the effect, so that when the wearer was suddenly attacked by some disorder for which jade was a cure, his system would have become so habituated to its action that it would no longer work as a remedy.[278] Of the _lapis nephriticus_ the old Danish writer, Caspar Bertholin, relates in 1628 that four prominent citizens of Copenhagen, whom he had recommended to wear it to break up the calculi with which they were afflicted, could testify to its worth, adding, somewhat naïvely, “at least two of them can, for the two others are dead—but not of the stone.” He himself, however, although he had sent for specimens at great expense, to Venice, Nuremberg and Batavia, could not gain any relief from his trouble, but nevertheless, firm in his conviction of the special curative power of jade, he asserts that the calculi which tormented him must have been exceptionally hard and flint-like, so that they could not be broken up. The vogue enjoyed by this supposed remedy in the Denmark of the time is illustrated in the case of the reigning sovereign, Christian IV, who wore on his person a green nephrite until the day of his death. This stone is still preserved in the Rosenborg Museum collection among the relics of this king.[279] [Illustration: FRONTISPIECE OF MUSEUM WORMIANUM Printed in Leyden in 1655, showing a part of the remarkable collection of specimens illustrating natural history owned by Olaus Wormius of Copenhagen. ] Johannes de Laet was much impressed with the virtues of the _lapis nephriticus_ as were most of his learned contemporaries, since he assures his readers that an oblong, smooth, moderately thick stone in his possession, having the color of honey and a very oily surface, had given his wife great relief from the severe pains caused by renal calculus, when the stone was bound upon her wrist. This particular specimen he sent a few years later to his Danish friend, Ole Worms, for the latter’s cabinet of natural history. De Laet writes that all the virtues claimed for nephrite by Monardes in 1574, were observable in his specimen.[280] As late as 1726, there were some who retained faith in the curative power of jade, for a record of that date informs us that the traveller Paul Lucas had just come back to Paris from the Orient, and had brought with him a specimen of the lapis nephriticus which he intended to have cut up into thin slabs to bestow upon such of his friends as were suffering from gravel or calculus, or similar troubles.[281]