Science is not perfect. It's often misused; it's only a tool, but it's the best tool we have. Self-correcting , ever changing, applicable to everything: with this tool, we vanquish the impossible.

In Italy, the Inquisition was condemning people to death until the end of the eighteenth century, and inquisitional torture was not abolished in the Catholic Church until 1816. The last bastion of support for the reality of witchcraft and the necessity of punishment has been the Christian churches.

Science ... looks skeptically at all claims to knowledge, old and new. It teaches not blind obedience to those in authority but to vigorous debate, and in many respects that's the secret of its success.

There is much that science doesn't understand, many mysteries still to be resolved. In a Universe tens of billions of light-years across and some ten or fifteen billion years old, this may be the case forever. We are constantly stumbling on new surprises

The gears of poverty, ignorance, hopelessness and low self-esteem interact to create a kind of perpetual failure machine that grinds down dreams from generation to generation. We all bear the cost of keeping it running. Illiteracy is its linchpin.

For me, the most ironic token of [the first human moon landing] is the plaque signed by President Richard M. Nixon that Apollo 11 took to the moon. It reads, ‘We came in peace for all Mankind.’ As the United States was dropping seven and a half megatons of conventional explosives on small nations in Southeast Asia, we congratulated ourselves on our humanity. We would harm no one on a lifeless rock.

The wind whips through the canyons of the American Southwest, and there is no one to hear it but us - a reminder of the 40,000 generations of thinking men and women who preceded us, about whom we know almost nothing, upon whom our civilization is based.