“How much intelligence does it take to sneak up on a leaf?”

“One mark of a good officer, he remembered, was the ability to make quick decisions. If they happen to be right, so much the better”

“The Product of Freedom and Security is a constant (F X S = k). Giving up freedom for security is beginning to look naive.”

“I myself have dreamed up a structure intermediate between Dyson spheres and planets. Build a ring 93 million miles in radius - one Earth orbit - around the sun. If we have the mass of Jupiter to work with, and if we make it a thousand miles wide, we get a thickness of about a thousand feet for the base.And it has advantages. The Ringworld will be much sturdier than a Dyson sphere. We can spin it on its axis for gravity. A rotation speed of 770 m/s will give us a gravity of one Earth normal. We wouldn't even need to roof it over. Place walls one thousand miles high at each edge, facing the sun. Very little air will leak over the edges.Lord knows the thing is roomy enough. With three million times the surface area of the Earth, it will be some time before anyone complains of the crowding.”

“Spray a book with insect spray, drop it in a bag, add some mothballs and seal it. Put it in another bag and seal it. Another. The packages piled up on the floor, each a book sealed in four plastic envelopes.”

“Long ago, Louis Wu had stood at the void edge of Mount Lookitthat. The Long Fall River, on that world, ends in the tallest waterfall in known space. Louis's eyes had followed it down as far as they could penetrate the void mist. The featureless white of the void itself had grasped at his mind, and Louis Wu, half hypnotized, had sworn to live forever. How else could he see all there was to see?Now he reaffirmed that decision.”

“The gods do not protect fools. Fools are protected by more capable fools.”