The saddest aspect of life right now is that science gathers knowledge faster than society gathers wisdom.

Until now in world's history, whenever we've had a dark age, its been temporary and local. And other parts of the world have been doing fine. And eventually, they help you get out of the dark age. We are now facing a possible dark age which is going to be world-wide and permanent! That's not fun. That's a different thing. But once we have established many worlds, we can do whatever we want as long as we do it one world at a time.

Since emotions are few and reasons are many (said the robot Giscard) the behavior of a crowd can be more easily predicted than the behavior of one person.

I would argue that a truly developed country would be beyond Presidents and Kings. In a world with some semblance of equality, each liberal-minded woman, each gay person, and indeed almost every person could be their own President. In a world of equals, what real service does a ruler provide?

At two-tenths the speed of light, dust and atoms might not do significant damage even in a voyage of 40 years, but the faster you go, the worse it is--space begins to become abrasive. When you begin to approach the speed of light, hydrogen atoms become cosmic-ray particles, and they will fry the crew. ...So 60,000 kilometers per second may be the practical speed limit for space travel.

Plate glass... has no beauty of its own. Ideally, you ought not to be able to see it at all, but through it you can see all that is happening outside. That is the equivalent of writing that is plain and unadorned. Ideally, in reading such writing, you are not even aware that you are reading. Ideas and events seem merely to flow from the mind of the writer into that of the reader without any barrier between. I hope that is what is happening when you read this book

I'm an indoors person. I'm not afraid of the outdoors and I penetrate it easily and cheerfully. However, I must admit I like Central Park better than the wilderness, and I like the canyons of Manhattan better than Central Park, and I like the interior of my apartment better than the canyons of Manhattan, and I like my two rooms better with the shades down at all times than with the shades up. I'm not an agoraphobe at all, but I am a claustrophile, if you see the distinction.