Avoidable human misery is more often caused not so much by stupidity as by ignorance, particularly our ignorance about ourselves.

We are the only species on the planet, so far as we know, to have invented a communal memory stored neither in our genes nor in our brains. The warehouse of this memory is called the library

The Apollo pictures of the whole Earth conveyed to multitudes something well known to astronomers: On the scale of the worlds - to say nothing of stars or galaxies - humans are inconsequential, a thin film of life on an obscure and solitary lump of rock and metal

There are wonders enough out there without our inventing any.

Science is based on experiment, on a willingness to challenge old dogma, on an openness to see the universe as it really is. Accordingly, science sometimes requires courage - at the very least the courage to question the conventional wisdom.

The nuclear arms race is like two sworn enemies standing waist deep in gasoline, one with three matches, the other with five.

We are not smart enough to decide which pieces of knowledge are permissible and which are not.