Modern science has been a voyage into the unknown, with a lesson in humility waiting at every stop. Many passengers would rather have stayed home. - Carl Sagan

Modern science has been a voyage into the unknown, with a lesson in humility waiting at every stop.

One of the saddest lessons of history is this: If we’ve been bamboozled long enough, we tend to reject any evidence of the bamboozle. We’re no longer interested in finding out the truth. The bamboozle has captured us. It’s simply too painful to acknowledge, even to ourselves, that we’ve been taken. Once you give a charlatan power over you, you almost never get it back. So the old bamboozles tend to persist as the new ones rise.

I would love to believe that when I die I will live again, that some thinking, feeling, remembering part of me will continue. But as much as I want to believe that, and despite the ancient and worldwide cultural traditions that assert an afterlife, I know of nothing to suggest that it is more than wishful thinking. I want to grow really old with my wife, Annie, whom I dearly love. I want to see my younger children grow up and to play a role in their character and intellectual development. I want to meet still unconceived grandchildren. There are scientific problems whose outcomes I long to witness — such as the exploration of many of the worlds in our Solar System and the search for life elsewhere. I want to learn how major trends in human history, both hopeful and worrisome, work themselves out: the dangers and promise of our technology, say; the emancipation of women; the growing political, economic, and technological ascendancy of China; interstellar flight. If there were life after death, I might, no matter when I die, satisfy most of these deep curiosities and longings. But if death is nothing more than an endless dreamless sleep, this is a forlorn hope. Maybe this perspective has given me a little extra motivation to stay alive. The world is so exquisite, with so much love and moral depth, that there is no reason to deceive ourselves with pretty stories for which there's little good evidence. Far better, it seems to me, in our vulnerability, is to look Death in the eye and to be grateful every day for the brief but magnificent opportunity that life provides.

We have held the peculiar notion that a person or society that is a little different from us, whoever we are, is somehow strange or bizarre, to be distrusted or loathed. Think of the negative connotations of words like alien or outlandish. And yet the monuments and cultures of each of our civilizations merely represent different ways of being human. An extraterrestrial visitor, looking at the differences among human beings and their societies, would find those differences trivial compared to the similarities. The Cosmos may be densely populated with intelligent beings. But the Darwinian lesson is clear: There will be no humans elsewhere. Only here. Only on this small planet. We are a rare as well as an endangered species. Every one of us is, in the cosmic perspective, precious. If a human disagrees with you, let him live. In a hundred billion galaxies, you will not find another.