Zymotic diseases smite down the aged and young, but, when you have learnt that they are caused by myriads of invisible germs which float in the water or the air, you have but to observe the commonest rules of sanitary science, to filter and boil the dangerous water, to insure free currents of air, to breathe as nature meant you to breathe, through the nostrils, and not through the throat, and you rob them of half their deadliness. Why has smallpox been stayed in its loathly ravages, and deprived of its hideous power? Why does the Black Death rage no longer, as it raged among the monks of this Abbey four centuries ago? Why do we not have pestilence, like that great plague of London, which destroyed 7,165 persons in a single week? Why has jail fever disappeared? Why are the cities of Europe horrified no longer by the hideousness of medieval leprosy? Because men live amid cleaner and purer surroundings. Because rushes are no longer strewn over floors which had been suffered to be saturated with the organic refuse of years. Because the simplest laws of nature are better understood. Because, in these respects, men have remedied by God's aid, some of those miseries for which the Savior sighed. And this amelioration of man's miseries is a great, and noble, and Christlike work. Would that there were no other side to the picture! Man, alas! also has done, and may do, infinite mischief to the world he lives in. He may cut down the forests on the hills, and so diminish the necessary rain. He may pluck up the grasses on the shore, and so lay waste whole acres to the devastating sands. He may poison the sweet, pure rivers of his native soil, till their crystal freshness is corrupted into deathful and putrescent slime. He may herd together, as we suffer our poor to do, in filthy tenements which shall breed every species of disease and vice. He may indulge or acquiesce in senseless fashions and pernicious vanities which shall mean not only wasteful ugliness and grotesque extravagance, but leave shattered health and ruined lives, to the mothers of his race. He may in greed of competition extirpate the game of the forest, the fishes of the sea. He may destroy the exquisite balance of nature, by shooting down or entrapping the sweet birds of the air, till his vines and his harvests are devastated by the insects on which they feed. He may suffer the chimneys of his manufactories to poison the atmosphere with black smoke and sulphurous acid, till his proudest cities are stifled at noonday, as we all have seen in London for these many weeks, with the unclean mirk of midnight fogs. He may suffer noxious gases to be vomited upon the breeze, till the most glorious buildings in his cities corrode and crumble--as the stones of this Abbey are doing--under their influence,--till the green woods blacken into leafless wastes, and life is lived at miserable levels of vitality under the filthy reek. There is hardly any limit to the evil, no less than to the good, which man