We seem, these days, much more willing to recognize the perils before us than we were even a decade ago. The newly recognized dangers threaten all of us, equally. No one can say how it will turn out down here. But this is also, we may note, the first time that a species has become able to journey to the planets and the stars. Sailors on a becalmed sea, we sense a stirring of the breeze.

The significance of our lives and our fragile planet is then determined only by our own wisdom and courage. We are the custodians of life's meaning. We long for a Parent to care for us, to forgive us our errors, to save us from our childish mistakes. But knowledge is preferable to ignorance. Better by far to embrace the hard truth than a reassuring fable. If we crave some cosmic purpose, then let us find ourselves a worthy goal.

By looking far out into space we are also looking far back into time, back toward the horizon of the universe, back toward the epoch of the Big Bang.

Writing is perhaps the greatest of human inventions, binding together people who never knew each other, citizens of distant epochs. Books break the shackles of time. A book is proof that humans are capable of magic.

National boundaries are not evident when we view the Earth from space. Fanatical ethnic or religious or national chauvinisms are a little difficult to maintain when we see our planet as a fragile blue crescent fading to become an inconspicuous point of light against the bastion and citadel of the stars.

I would love to believe that when I die I will live again, that some thinking, feeling, remembering part of me will continue.

There are many hypotheses in science which are wrong. That’s perfectly all right: it’s the aperture to finding out what’s right. Science is a self-correcting process.