The rule of sleep is not the same for all. There are some with whom its requirements are gentle: a few hours will suffice. But such cases are exceptional. The Jesuits have done much for education, but on this question they seem to have failed. In settling the system for their college at Clermont, they followed their physicians in a rigid rule. The latter reported that five hours were sufficient, six abundant, and seven as much as a youthful constitution could bear without injury. On the other hand, Cobbett, whose experience of life was as thorough as his diligence, says expressly: "Young people require more sleep than those that are grown up: there must be the number of hours, and that number cannot well be on an average less than eight; and if it be more in winter-time, it is all the better."[137] George the Third thought otherwise, at least for men. A tradesman, whom he had asked to call on him at eight o'clock in the morning, arriving behind the hour, the King said, "Oh! the great Mr. B.! What sleep do you take, Mr. B.?" "Why, please your Majesty, I am a man of regular habits; I usually take eight hours." "Eight hours!" said the King; "that's too much, too much. Six hours' sleep is enough for a man, seven for a woman, and eight for a fool,--Mr. B., eight for a fool." The opinions of physiologists would probably incline with Mr. B., the tradesman, contrary to this royal authority. [137] Advice to Young Men, p. 33. It is impossible to lay down any universal rule with regard to the proper portion of time for sleep. Each constitution of body has its own habits; nor can any rule be drawn from the lives of the most industrious, except of economy of time, according to the capacity of each person. The great German scholar Heyne, who has shed such lustre on classical learning, in the order of his early studies allowed himself, for six months, only two nights' sleep in a week. The eccentric Robert Hill, of England, who passed his life as a tailor, but by persevering labor made rare attainments in Latin, Greek, and Hebrew, was accustomed to sit up very late into the night, or else to rise by two or three o'clock in the morning, that he might find time for reading without prejudice to his trade, and although of a weakly constitution, he accustomed himself to do very well with only two or three hours of sleep in the twenty-four, and he lived to be seventy-eight. But this is a curiosity rather than an example. Such also is the story of the Roman Emperor Caligula, who slept only three hours. In the list of men sleeping only four hours is Frederick of Prussia, John Hunter, the surgeon, Napoleon, and Alexander von Humboldt. That gallant cavalier and accomplished historian, renowned for genius and misfortune, Sir Walter Raleigh, was accustomed, even under the pressure of his arduous career, to devote four hours daily to reading and study, while he allowed only five for sleep. Probably