Chlorine is a deadly poison gas employed on European battlefields in World War I. Sodium is a corrosive metal which burns upon contact with water. Together they make a placid and unpoisonous material, table salt. Why each of these substances has the properties it does is a subject called chemistry.

While our behavior is still significantly controlled by our genetic inheritance, we have, through our brains, a much richer opportunity to blaze new behavioral and cultural pathways on short timescales.

Demon mean knowledge in Greek, especially about the material world. Science means knowledge in Latin. A jurisdictional dispute is exposed, even if we look no further

The usual rejoinder to someone who says 'They laughed at Columbus, they laughed at Galileo' is to say 'But they also laughed at Bozo the Clown'.

The Earth is the only world known so far to harbor life. There is nowhere else, at least in the near future, to which our species could migrate. Visit, yes. Settle, not yet. Like it or not, for the moment the Earth is where we make our stand. It has been said that astronomy is a humbling and character-building experience..... To me, it underscores our responsibility to deal more kindly with one another, and to preserve and cherish the pale blue dot, the only home we've ever known.

The immense distances to the stars and the galaxies mean that we see everything ins pace int he past, some as they were before the Earth came to be. Telescopes are time machines.

In our time, we have sifted the sands of Mars, we have established a presence there, we have fulfilled a century of dreams!