Teller contended, not implausibly, that hydrogen bombs keep the peace, or at least prevent thermonuclear war, because the consequences of warfare between nuclear powers are now too dangerous. We haven't had a nuclear war yet, have we? But all such arguments assume that the nuclear-armed nations are and always will be, without exception, rational actors, and that bouts of anger and revenge and madness will never overtake their leaders (or military and secret police officers in charge of nuclear weapons). In the century of Hitler and Stalin, this seems ingenuous.

Man is the matter of the cosmos, contemplating itself.

The Cosmos is all that is or was or ever will be. Our feeblest contemplations of the Cosmos stir us -- there is a tingling in the spine, a catch in the voice, a faint sensation, as if a distant memory, of falling from a height. We know we are approaching the greatest of mysteries.

After the earth dies, some 5 billion years from now, after it's burned to a crisp, or even swallowed by the Sun, there will be other worlds and stars and galaxies coming into being - and they will know nothing of a place once called Earth.

The desire to be connected with the cosmos reflects a profound reality, but we are connected; not in the trivial ways that astrology promises, but in the deepest ways.

Accommodation to change, the thoughtful pursuit of alternative futures are keys to the survival of civilization and perhaps of the human species.

For all our failings, despite our limitations and fallibilities, we humans are capable of greatness.