Let me end with... man's ageless fantasy, to fly to the moon.... Plutarch and Lucian, Ariosto and Ben Jonson wrote about it, before the days of Jules Verne and H. G. Wells and science fiction. The seventeenth century was heady with... fables about voyages to the moon. Kepler wrote one full of deep scientific ideas... wrote... The Discovery of a New World. They did not draw a line between science and fancy... they all tried to guess where... earth's gravity would stop. Only Kepler understood that gravity has no boundary, and put a law to it-... the wrong law.
All this was a few years before Isaac Newton was born, and it was all in his head that day in 1666, when he... came to conceive... that the moon is like a ball... thrown so hard that it falls exactly as fast as the horizon... he went on to calculate how long... the distant moon would take to round the earth... [T]he imagination that day chimed with nature, and made a harmony.