The difference between machines and human beings is that human beings can be reproduced by unskilled labour.

The entire sweep of human history from the dark ages into the unknown future was considerably less important at the moment than the question of a certain girl and her feelings toward him.

The universe must be full of voices, calling from star to star in a myriad tongues. One day we shall join that cosmic conversation.

If man can live in Manhattan, he can live anywhere.

All explorers are seeking something they have lost. It is seldom that they find it, and more seldom still that the attainment brings them greater happiness than the quest.

Anything that is theoretically possible will be achieved in practice, no matter what the technical difficulties are, if it is desired greatly enough.

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