"The old man smiled. ‘I shall not die of a cold, my son. I shall die of having lived.’"
"When you view the Earth from farther away, as the Apollo astronauts did, it shrinks in apparent size, until nothing but a little geography remains. You’re struck by how self-contained it is. An occasional hydrogen atom leaves; a pitter-patter of cometary dust arrives. Sunlight, generated in the immense, silent thermonuclear engine deep in the solar interior, pours out of the Sun in all directions, and the Earth intercepts enough of it to provide a little illumination and enough heat for our modest purposes. Apart from that, this small world is on its own."