During the past fourteen years, since the entry of the United States into the Second World War, and especially since the end of the war (with its disillusioning peace blending into the so-called cold war), the United States has had thrust upon it the problems of the overwhelming difficulties of world leadership. Leadership in the true sense of the word cannot be totalitarian or authoritarian. It must be intellectual, moral and spiritual. This our leading statesmen have sometimes recognized, though not, I am inclined to think, often enough. In any event, it is in these spheres that our peoples have been perhaps the least prepared for our mission. Even in the natural sciences, one of the principal creative sources of American leadership has been individual scientists—such as Einstein, Fermi and Teller—bom and trained in Europe, who found asylum in the United States from Nazi or Fascist tyranny. In so far as the creative mind and its place in the national life are concerned, our main weakness has not been, however, in the natural sciences. During the first half of the twentieth century in the United States these have become distinguished in their own right. When it comes to the practical application of science we have led the world. In no other country have the results of new scientific knowledge been utilized technologically to produce as high a standard of living, measured in material quantity, as in the United States.