The dinosaurs disappeared because they could not adapt to their changing environment. We shall disappear if we cannot adapt to an environment that now contains spaceships, computers - and thermonuclear weapons.

They had not yet attained the stupefying boredom of omnipotence; their experiments did not always succeed.

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

The exploration of the planets is now closer to us in time than the exploration of Africa by Stanley and Livingstone.

Death focuses the mind on the things that really matter: why are we here, and what should we do?

Those wanderers must have looked on Earth, circling safely in the narrow zone between fire and ice, and must have guessed that it was the favourite of the Sun's children.

It may be that our role on this planet is not to worship God - but to create him.