We can always take but never give.

Each of us is a tiny being, permitted to ride on the outermost skin of one of the smaller planets for a few dozen trips around the local star.

Scientists make mistakes. Accordingly, it is the job of the scientist to recognize our weakness, to examine the widest range of opinions, to be ruthlessly self-critical. Science is a collective enterprise with the error-correction machinery often running smoothly.

A celibate clergy is an especially good idea, because it tends to suppress any hereditary propensity toward fanaticism.

Except in pure mathematics, nothing is known for certain (although much is certainly false).

Our ancestors lived out of doors. They were as familiar with the night sky as most of us are with our favorite television programs.

The library connects us with the insight and knowledge, painfully extracted from Nature, of the greatest minds that ever were, with the best teachers, drawn from the entire planet and from all our history, to instruct us without tiring, and to inspire us to make our own contribution to the collective knowledge of the human species.