It's hard to kill a creature once it lets you see its consciousness.

Nevertheless, (Jefferson) believed that the habit of skepticism is an essential prerequisite for responsible citizenship. He argued that the cost of education is trivial compared to the cost of ignorance, of leaving government to the wolves. He taught that the country is safe only when the people rule.

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.

Books permit us to voyage through time, to tap the wisdom of our ancestors.

Be grateful everyday for the brief but magnificent opportunity that life provides.

We live in a vast and awesome universe in which, daily, suns are made and worlds destroyed, where humanity clings to an obscure clod of rock.

In the deepest sense the search for extraterrestrial intelligence is a search for ourselves.