The first years of man must make provision for the last. He that never thinks, never can be wise. Perpetual levity must end in ignorance; and intemperance, though it may fire the spirits for an hour, will make life short or miserable.
 Samuel Johnson, The History of Rasselas, Prince of Abissinia (1759). copy citation

Context

““ Happiness, ” said he, “ must be something solid and permanent, without fear and without uncertainty. ” “ My friends, ” said he, “ I have seriously considered our manners and our prospects, and find that we have mistaken our own interest. The first years of man must make provision for the last. He that never thinks, never can be wise. Perpetual levity must end in ignorance; and intemperance, though it may fire the spirits for an hour, will make life short or miserable. Let us consider that youth is of no long duration, and that in mature age, when the enchantments of fancy shall cease, and phantoms of delight dance no more about us, we shall have no comforts but the esteem of wise men and the means of doing good.” source