That series of inventions by which man from age to age has remade his environment is a different kind of evolution -- not biological, but cultural evolution . . . "The Ascent of Man.

Dissent is the native activity of the scientist, and it has got him into a good deal of trouble in the last years. But if that is cut off, what is left will not be a scientist. And I doubt whether it will be a man.

We have to understand that the world can only be grasped by action, not by contemplation. The hand is more important than the eye ... The hand is the cutting edge of the mind.

Nations in their great ages have not been great in art or science, but in art and science.

The largest single step in the ascent of man is the change from nomad to village agriculture.

Ask an impertinent question and you are on the way to the pertinent answer.

The idea that the universe is running down comes from a simple observation about machines. Every machine consumes more energy than it renders.