The goal of the future is full unemployment, so we can play. That's why we have to destroy the present politico-economic system.

We stand now at the turning point between two eras. Behind us is a past to which we can never return... The coming of the rocket brought to an end a million years of isolation... the childhood of our race was over and history as we know it began.

All human plans [are] subject to ruthless revision by Nature, or Fate, or whatever one preferred to call the powers behind the Universe.

When you finally understand the universe, it will not only be stranger than you imagine, it will be stranger than you can imagine.

I have never grown up, but I will never stop growing.

Good morning, Dr. Chandra. This is Hal. I am ready for my first lesson.

It was one thing to have guessed it, another to have had that guess confirmed beyond possibility of refutation.