The second half of the twentieth century seems to mark another turning point in the history of humanity. Whether the decades ahead of us will raise the world to a higher level of civilization or throw it back into an era of primitive savagery or even destroy humankind physically, we cannot know. But this very ignorance reveals more than the trivial fact that in some manner the future is always unknown. This ignorance itself is a consequence of the transformation which is upon us. Less and less, the future will be dominated by impersonal natural and social processes, the course of which we could anticipate by extrapolating past experience. In quite a new sense it will be the product of human choices — even if we choose to remain passive.