By exploring other worlds we safeguard this one. By itself, I think this fact more than justifies the money our species has spent in sending ships to other worlds. It is our fate to live during one of the most perilous and, at the same time, one of the most hopeful chapters in human history.

Frederick Douglas taught that literacy is the path from slavery to freedom. There are many kinds of slavery and many kinds of freedom, but reading is still the path.

There are as many atoms in one molecule of DNA as there are stars in a typical galaxy.

We need to reduce military budgets; raise living standards; engender respect for learning; support science, scholarship, invention, and industry; promote free inquiry; reduce domestic coercion; involve the workers more in managerial decisions; and promote genuine respect and understanding derived from an acknowledgement of our common humanity and our common jeopardy.

Not all bits have equal value.

Since, in the long run, every planetary society will be endangered by impacts from space, every surviving civilization is obliged to become spacefaring — not because of exploratory or romantic zeal, but for the most practical reason imaginable: staying alive.

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'.