Dreams have been considered as prescriptive in various diseases. Diodorus Siculus relates that a certain Scythian dreamed that Aesculapius had drawn the humours of his body to one place, or head, to have it lanced. When Galen had an inflammation of the diaphragm, we are told that he was directed in a dream to open a vein between the thumb and the fourth finger--an operation which restored him to health. Marcus Antoninus asserted that he learned in his dreams various remedies for spitting of blood. It is related of Sir Christopher Wren, that, when at Paris, in 1671, being disordered with "a pain in his reins," he sent for a physician, who prescribed blood-letting, but he deferred submitting to it, and dreamed that very night that he was in a place where palm-trees grew, and that a woman in a romantic habit offered dates to him. The next day he sent for dates, which cured him. Now, although this cure, brought about by a dream, was considered wonderful, its circumstances offer nothing supernatural. It is more than probable that Sir Christopher had frequently read in foreign works on medicine, that dates were recommended as an efficacious remedy in nephritic complaints; and, moreover, had met in his daily perambulations female quacks, who exhibit themselves to this day in the French metropolis, fantastically attired, and vending their far-famed nostrums. That he should have remembered dates, and that the phantasm of the she-mountebank might at the same time have struck his fancy, were two associations by no means improbable. It is very likely that all the strange stories of prophetic dreams might be traced to a similar connexion of ideas. I have before observed that dreams do not always assume their complexion from recent occurrences, and our bodily sufferings during sleep bring to our recollection every circumstance that regards the malady. A patient who had a bottle of hot water placed at his feet dreamed that he was walking in great agony in the burning lava of Vesuvius. Similar associations exist when awake: the man whose arm has been amputated constantly refers the pain he experiences to the lost hand, or to that part of the limb which received the injury; and the very same nervous illusion prevails during his slumbers. A case is recorded of an officer who had lost his leg, and, when cold, felt comfort and warmth by wrapping the stump of his wooden leg in flannel.