It is No Accident that We Inhabit a Veritable Paradise

Imagine a spaceship full of sleeping explorers, deep-frozen would-be colonists of some distant world. Perhaps the ship is on a forlorn mission to save the species before an unstoppable comet, like the one that killed the dinosaurs, hits the home planet. The voyagers go into the deep-freeze soberly reckoning the odds against their spaceship's ever chancing upon a planet friendly to life. If one in a million planets is suitable at best, and it takes centuries to travel from each star to the nex...

 Carl Sagan's Vision of the Human Race's Future

We were hunters and foragers. The frontier was everywhere. We were bounded only by the Earth and the ocean and the sky. The open road still softly calls. Our little terraqueous globe as the madhouse of those hundred thousand millions of worlds. We who cannot even put our own planetary home in order, riven with rivalries and hatreds, are we to venture out into space? By the time we're ready to settle even the nearest other planetary systems, we will have changed. The simple passage of so many...