During the retreat of the French from Russia the poor sufferers, frozen and famished, were continually tormented by similar hallucinations, which increased their sufferings at times to such a degree as to lead them to commit suicide. Another frequent cause of visions is long-continued fasting combined with more or less ascetic devotion. This is said to explain why the prophets of the Old Testament were so vigorously forbidden to indulge in wine or rich fare. Thus Aaron was told: "Do not drink wine nor strong drink, thou nor thy sons with thee, when ye go into the tabernacle" (Levit. x. 9); Moses remained forty days, and "neither did eat bread nor drink wine," when he was on Mount Sinai (Deuter. ix. 9); the Nazarites were ordered not to "drink any liquor of grapes, nor to eat moist grapes or dried," and even to abstain from vinegar (Numbers vi. 3), and Daniel and his companions had nothing but "pulse to eat and water to drink" (Dan. i. 12), in order to prepare them for receiving "wisdom and knowledge and the understanding of dreams and visions." Narcotics also, and, in our day, most of the anæsthetics can produce visions and hallucinations, but the result is in all such cases much less interesting than when they are produced spontaneously. Tobacco and opium, betel, hasheesh, and coca are the principal means employed; but Siberia has besides its narcotic mushrooms, Polynesia its ava, New Granada and the Himalaya the thorn-apple, Florida its emetic apalachine, and the northern regions of America and Europe have their ledum. The most effective among these narcotics seems to be the Indian hemp, since the visions it produces surpass even the marvelous effects of opium, as has been recently again most graphically described by Bayard Taylor. Laughing-gas, also, has frequently similar effects, and affords, besides, the precious privilege of freedom from the painful, often excruciating consequences of other narcotics. When perfumes are employed for the express purpose of producing visions, it is difficult to ascertain how much is due to their influence, and how much to the over-excited mind of the seer. Benvenuto Cellini describes--though probably not in the most trustworthy manner--the amazing effect produced upon himself and a boy by his side, by the perfumes which a priest burnt in the Coliseum. The whole vast building seemed to him filled with demons, and the boy saw thousands of threatening men, four huge giants, and fire bursting out in countless places. The great artist was told, at the same time, that a great danger was threatening him, and that he would surely lose his beloved Angelica within the month; both events occurred as predicted, and thus proved that in this case at least magic phenomena had accompanied the visions. (_Goethe, B. Cellini_, l. iv. ch. 2.)