Sleep is a state in which a great part of every life is passed.  No animal has been yet discovered, whose existence is not varied with intervals of insensibility; and some late philosophers have extended the empire of sleep over the vegetable world.

Yet of this change, so frequent, so great, so general, and so necessary, no searcher has yet found either the efficient or final cause; or can tell by what power the mind and body are thus chained down in irresistible stupefaction; or what benefits the animal receives from this alternate suspension of its active powers.

Whatever may be the multiplicity or contrariety of opinions upon this subject, nature has taken sufficient care that theory shall have little influence on practice.  The most diligent inquirer is not able long to keep his eyes open; the most eager disputant will begin about midnight to desert his argument; and, once in four-and-twenty hours, the gay and the gloomy, the witty and the dull, the clamorous and the silent, the busy and the idle, are all overpowered by the gentle tyrant, and all lie down in the equality of sleep.

Philosophy has often attempted to repress insolence, by asserting, that all conditions are levelled by death; a position which, however it may deject the happy, will seldom afford much comfort to the wretched.  It is far more pleasing to consider, that, sleep is equally a leveller with death; that the time is never at a great distance, when the balm of rest shall be diffused alike upon every head, when the diversities of life shall stop their operation, and the high and the low shall lie down together[1].

It is somewhere recorded of Alexander, that in the pride of conquests, and intoxication of flattery, he declared that he only perceived himself to be a man by the necessity of sleep.  Whether he considered sleep as necessary to his mind or body, it was indeed a sufficient evidence of human infirmity; the body which required such frequency of renovation, gave but faint promises of immortality; and the mind which, from time to time, sunk gladly into insensibility, had made no very near approaches to the felicity of the supreme and self-sufficient nature.

I know not what can tend more to repress all the passions, that disturb the peace of the world, than the consideration that there is no height of happiness or honour, from which man does not eagerly descend to a state of unconscious repose; that the best condition of life is such, that we contentedly quit its good to be disentangled from its evils; that in a few hours splendour fades before the eye, and praise itself deadens in the ear; the senses withdraw from their objects, and reason favours the retreat.

What then are the hopes and prospects of covetousness, ambition, and rapacity?  Let him that desires most have all his desires gratified, he never shall attain a state which he can, for a day and a night, contemplate with satisfaction, or from which, if he had the power of perpetual vigilance, he would not long for periodical separations.