The difference between machines and human beings is that human beings can be reproduced by unskilled labour.

The difference between machines and human beings is that human beings can be reproduced by unskilled labour.

In my life I have found two things of priceless worth - learning and loving. Nothing else - not fame, not power, not achievement for its own sake - can possible have the same lasting value. For when your life is over, if you can say 'I have learned' and 'I have loved,' you will also be able to say 'I have been happy.

The numbers of distinct human societies or nations, when our race is twice its present age, may be far greater than the total number of all the men who have ever lived up to the present time.

The choice, as Wells once said, is the Universe-or nothing. . . . The challenge of the great spaces between the worlds is a stupendous one; but if we fail to meet it, the story of our race will be drawing to its close. Humanity will have turned its back upon the still untrodden heights and will be descending again the long slope that stretches, across a thousand million years of time, down to the shores of the primeval sea.

The Shuttle is to space flight what Lindbergh was to commercial aviation.

You will find men like him in all of the world's religions. They know that we represent reason and science, and, however confident they may be in their beliefs, they fear that we will overthrow their gods. Not necessarily through any deliberate act, but in a subtler fashion. Science can destroy a religion by ignoring it as well as by disproving its tenets. No one ever demonstrated, so far as I am aware, the nonexistance of Zeus or Thor, but they have few followers now.