Let us think of the human being, not in an abstract and general way, but in the most concrete possible, the most personal fashion. Let us think of this certain old man we have known for years in the country, —this old farmer with his wrinkled face, his keen eyes which have beheld so many harvests and so many earthly horizons, his long habits of patience and suffering, courage, poverty and noble labor, a man perhaps like those parents of a great living American statesman whose photographs appeared some months ago in a particularly moving copy of a weekly magazine. Or let us think of this certain boy or this girl who are our relatives or our friends, whose everyday life we well know, and whose loved appearance, whose soft or husky voice is enough to rejoice our hearts. Let us remember—remember in our heart—a single gesture of the hand, or the smile in the eyes of one we love. What treasures on earth, what masterpieces of art or of science, could pay for the treasures of life, feeling, freedom and memory, of which this gesture, this smile is the fugitive expression? We perceive intuitively, in an indescribable not inescapable flash, that nothing in the world is more precious than one single human being. I am well aware how many difficult questions come to mind at the same time and I shall come back to these difficulties, but for the present I wish only to keep in mind this simple and decisive intuition, by means of which the incomparable value of the human person is revealed to us. Moreover, St. Thomas Aquinas warns us that the Person is what is noblest and most perfect in the whole of nature.