Probably a dozen times since their death I've heard my mother or father, in an ordinary conversational tone of voice, call my name. They had called my name often during my life with them ... It doesn't seem strange to me.

The well-meaning contention that all ideas have equal merit seems to me little different from the disastrous contention that no ideas have any merit.

I'd like the [Cosmos] series to be so visually stimulating that somebody who isn't even interested in the concepts will just watch for the effects. And I'd like people who are prepared to do some thinking to be really stimulated.

You have to know the past to understand the present.

Widespread intellectual and moral docility may be convenient for leaders in the short term, but it is suicidal for nations in the long term. One of the criteria for national leadership should therefore be a talent for understanding, encouraging, and making constructive use of vigorous criticism.

We began as wanderers, and we are wanderers still.

Some 5 billion years from now, there will be a last perfect day on Earth... then the sun will begin to die, life will be extinguished, the oceans will boil and evaporate away.