"Whether life exists elsewhere or not, man will never be entirely of the earth again. The sky above us is no longer a barrier but an endless ocean, and we stand on the shore, carefully testing the water. From our own planet, the moon, the other planets, and even the stars stretch out like a series of unknown islands, encouraging us to explore further. We have made our first brief, cautious voyage. The flags and machines that we have left on the moon will last for millions of years. Either they will be seen again by other men, or they will announce our existence and our accomplishment to other space travelers whose form we cannot even imagine. Like all great events in history, Apollo is a turning point, another fork in a long road. One road leads outward to further exploration and to new knowledge. The other road leads back to Earth and to ourselves, to a more intelligent operation of our planet. The lesson from Apollo is that neither road by itself is enough. From now on we must walk both roads."