One orbit, with a radius of 42,000 kilometers, has a period of exactly 24 hours. A body in such an orbit, if its plane coincided with that of the Earth's equator, would revolve with the Earth and would thus be stationary above the same spot on the planet. It would remain fixed in the sky of a whole hemisphere ... [to] provide coverage to half the globe, and for a world service three would be required, though more could be readily utilized. (1945) [Predidicting geosynchronous communication satellites]

The future is not to be forecast, but created.

Guns are the crutches of the impotent.

I don't pretend we have all the answers. But the questions are certainly worth thinking about.

Our own grandchildren may demonstrate that-sometimes- Gigantic is Beautiful.

The limits of the possible can only be defined by going beyond them into the impossible.

And because, in all the Galaxy, they had found nothing more precious than Mind, they encouraged its dawning everywhere. They became farmers in the fields of stars; they sowed, and sometimes they reaped. And sometimes, dispassionately, they had to weed.