Those worlds in space are as countless as all the grains of sand on all the beaches of the earth. Each of those worlds is as real as ours and every one of them is a succession of incidents, events, occurrences which influence its future. Countless worlds, numberless moments, an immensity of space and time. And our small planet at this moment, here we face a critical branch point in history, what we do with our world, right now, will propagate down through the centuries and powerfully affect the destiny of our descendants, it is well within our power to destroy our civilization and perhaps our species as well. - Carl Sagan