But all the remedies that originated in superstition were not entirely useless. Some, whether by accident or not, had a natural power of efficacy, and led to discoveries of importance. In the time of James I., a powder known as the sympathetic powder of Sir Kenelm Digby had a great reputation for healing wounds. Whenever a wound had been inflicted, this powder was applied to the weapon which had caused it, which was also smeared with ointment and dressed two or three times a day. The wound itself was directed to be brought together and carefully bound up with clean linen rags, but above all to be let alone for seven days, at the end of which time it was generally found to be healed. This was, of course, said to be due to the wonderful properties of the sympathetic powder, instead of the fact of excluding the air from the part and not interfering with nature’s own healing powers. The mysterious sympathetic healing powder was afterwards said to be simply calcined green vitriol. The rust of the spear of Telephus, alluded to by Homer as a cure for the wounds which that weapon inflicted, was probably verdigris, and led to the discovery of its use as a surgical dressing. The cures supposed to be performed by royal touch show the power of faith over desire, or mind over matter. The royal surgeons who introduced the patients to be touched for scrofula, doubtless took care to choose those who had a tendency to recover, and who, if left to nature, would probably have gradually recovered. Boswell says that Dr. Johnson, when thirty months old, was taken by his mother to London to be touched by Queen Anne, on the advice of Sir John Floyer, a physician of Lichfield.