Among other external causes which are apt to produce visions, must be mentioned violent motions, especially when they are revolving, as is the case with the Shamans of the Laplanders and the dancing Dervishes of the East; self-inflicted wounds, such as the priests of Baal caused in order to excite their power of divination, and long-continued imprisonment, as illustrated in the well-known cases of Benvenuto Cellini and Silvio Pellico. The latter was constantly tormented by sighs or suppressed laughter which he heard in his dungeon; then by invisible hands pulling at his dress, knocking down his books or trying to put out his light, till he began seriously to suspect that he might be the victim of invisible malignant powers. Fortunately all these phenomena disappeared at break of day, and thus his vigorous mind, supported by true piety, was enabled to keep his judgment uninjured. Diseases of every kind are a fruitful source of visions and some are rarely without them; but the character of visions differs according to the nature of the affections. Persons who suffer with the liver have melancholy, consumptive patients have cheerful visions. Epileptics often see fearful spectres during their paroxysms, and persons bitten by mad dogs see the animal that has caused their sufferings. The case of the bookseller Nicolai in Berlin is well known; the disease of which he suffered, is not only very common in some parts of Russia, but productive of precisely the same symptoms. The patients experience first a sensation of great despondency, followed by a period of profound melancholy, during which they see themselves surrounded by a number of persons, with whom they converse and quarrel, half conscious of their own delusion and yet not able to master it wholly. They are generally bled, whereupon the images become transparent and shrink into smaller and smaller space, till they finally disappear entirely. Affections of the heart and the subsequent unequal distribution of the blood through the system are apt to produce peculiar sounds, which at times fashion themselves into loud and harmonious pieces. The excitement usually attendant upon specially fatal plagues and contagious diseases increases the tendency which the latter naturally have to cause hallucinations. During a plague in the reign of Justinian, men were seen walking through the crowd and touching here and there a person; the latter were at once attacked by the disease and invariably succumbed. Upon another such occasion marks and spots appeared on the clothing of those who had caught the contagion, as if made by invisible hands, the sufferers began next to see a number of spectres and died in a short time. The same symptoms have accompanied the cholera in modern times, and more than once strange, utterly unknown persons were not only seen but heard, as they were conversing with others; what they said was written down in many cases, and proved to be predictions of approaching visits of the