"I have come to prefer something looser, a rough sort of definition which says simply that science fiction attempts to portray that which does not exist, a speculative reality, but endeavors to explore the consequences of such a speculation in a rigorous, systematic, and scientifically plausible way."

“Only a man who doubts his own bravery bristles when called a coward.”

“It is peaceful here. I am far from the fishmongers and the drainers and the wine-peddlers and all those others whose songs of commerce clang in the streets of cities. A man can think; a man can look within his soul, and find those things that have been the shaping of him, and draw them forth, and examine them, and come to know himself.”

“A man who lies to himself is the worst liar of all.”

“As we zoomed along on the Chaos Express, I was sometimes tempted toward godliness the way the godly are tempted toward sin. But my love of divine reason left me no way to opt for the irrational.”

“He didn’t have to observe the niceties of etiquette when talking to a computer.”

“What counts is what’s happening inside him, his own artistic fulfillment. If he can blow their skulls, that’s a bonus. But this is ecstasy. The whole universe is vibrating around him. A gigantic solo. God himself must have felt this way when he got to work on the first day.”