Two Arthur C. Clarke quotes for the price of one
"We cannot predict the new forces, powers, and discoveries that will be disclosed to us when we reach the other planets and set up new laboratories in space. They are as much beyond our vision today as fire or electricity would be beyond the imagination of a fish."
"If man survives for as long as the least successful of the dinosaurs - those creatures whom we often deride as nature's failures - then we may be certain of this: for all but a vanishingly brief instant near the dawn of history, the word 'ship' will mean - 'spaceship.'"