Who can read attentively the life of John Wesley, and not exclaim, if varied and exhausting labor, if perpetual excitement and constant drafts upon the brain, would ever wear a man out, he would have worn out? It was his creative energy that called into existence a denomination, his ardent piety that inspired it, his clear mind that legislated for it, his heroic industry that did no mean part of the incessant daily toil needful for its establishment. Yet this man of many labors, who through a long life never knew practically the meaning of the word _leisure_, says, at seventy-two, "How is it that I find the same strength that I did thirty years ago, that my nerves are firmer, that I have none of the infirmities of old age, and have lost several that I had in youth." And ten years later, he devoutly records, "Is anything too hard for God? It is now eleven years since I have felt such a thing as weariness." And he continued till eighty-eight in full possession of his faculties, laboring with body and mind alike to within a week of his death. Joseph Priestley was certainly a very different man, but scarcely less remarkable. No mean student in all branches of literature, a metaphysician, a theologian, a man of science, he began life with a feeble frame, and ended a hearty old age at seventy-one. He himself declares at fifty-four, that, "so far from suffering from application to study, I have found my health steadily improve from the age of eighteen to the present time." You would scarcely find a life more widely divided from these than that of Washington Irving. Nevertheless, it is like them in one respect, that it bears emphatic testimony to the real healthiness of mental exertion. He was the feeblest of striplings at eighteen. At nineteen, Judge Kent said, "He is not long for this world." His friends sent him abroad at twenty-one, to see if a sea voyage would not husband his strength. So pale, so broken, was he, that, when he stepped on board the ship, the captain whispered, "There is a chap who will be overboard before we are across!" Irving had, too, his share of misfortunes,--failure in business, loss of investments, in earlier life some anxiety as to the ways and means of support. Even his habits of study were hardly what the highest wisdom would direct. While he was always genial and social, and at times easy almost to indolence, when the mood seized him, he would write incessantly for weeks and even for months, sometimes fourteen, fifteen, or sixteen hours in a day. But he grew robust for half a century, and writes, at seventy-five, that he has now "a streak of old age." * * * * *