On this point much might be said, without exhausting the subject. But I have already observed that infants, when first born, require to sleep nearly their whole time. As they advance in years, the necessity for sleep; however, diminishes, until they come to maturity, when it remains for many years nearly stationary. In advanced age, the necessity for sleep again increases, till we reach the extremest old age, or what is usually called second childhood, when we again sometimes sleep nearly the whole time. I have already remarked that much might be said on this subject; but I do not think that the present occasion requires it. If the suggestions which are made in the chapter on "Early Rising" should receive the attention I flatter myself they merit, I do not believe children would often sleep too long. If, on the contrary, they are suffered to lie late in the morning, and then sit up late in the evening, all healthful habits and tendencies will he so deranged or broken up, that nature, in her indications, will by no means prove the unerring guide which she is wont to do in other circumstances. A few thoughts here, on the quantity of sleep required by the young after they approach maturity, may not be misplaced. Jeremy Taylor thought that for a healthy adult, three hours in twenty-four were enough for all the purposes of sleep. Baxter thought four hours about a reasonable time; Wesley, six; Lord Coke and Sir Wm. Jones, seven; and Sir John Sinclair, eight. These were the _theories_ of men who were all eminent for their learning, and most of them for their piety. How far their _practice_ corresponded with their theories, we are not, in every instance, told. But to come to the practice of several persons who have been distinguished in the world. General Elliot, one of the most vigorous men of his age, though living for his whole life on nothing but vegetables and water, and who at sixty-four had scarcely begun to feel the infirmities of old age, slept but four hours in twenty-four. Frederick the Great of Prussia, and the illustrious British surgeon, John Hunter, slept but five hours a day. Napoleon Bonaparte, for a great part of his life, slept only four hours; and Lord Brougham is said to require no more. Others, in numerous instances, require but six hours. But there are others still, who consume eight. The conclusion--in my own mind--is, that with a good constitution and active habits, men may habituate themselves to very different quantities of sleep. Still I think that six hours are little enough for most persons; and if a child, on arriving at maturity, is not inclined to sleep much longer than that, I should not regard him as wasting time. Most persons, it appears to me, require six hours of sound sleep in twenty-four;--I mean between the ages of twenty and seventy.