A vision of the future has been one of the sustaining marks of the American experience. Without that vision and without the men who devote themselves to realizing that vision, there can be no true American way of life. We must beware of the thoughtless men who proclaim that a particular stage of our social development, or any special set of conditions, is the best that progress can offer. These men would immobilize us in the great stream of history. They would let its great challenges and chances pass us by, . . . forgetting that the American way of life is a way of acting, not a state of inactivity.