Certainty ends inquiry.

A genius is a man who has two great ideas.

You will die but the carbon will not; its career does not end with you. It will return to the soil, and there a plant may take it up again in time, sending it once more on a cycle of plant and animal life.

Knowledge is an unending adventure at the edge of uncertainty.

The preoccupation with the choice of a mate both by male and female I regard as a continuing echo of the major selective force by which we have evolved.

Many theories of the ancient world seem terribly childish today, a hodge-podge of fables and false comparisons.But our theories will seem childish five-hundred years from now.Every theory is based on some analogy, and sooner or later the theory fails because the analogy turns out to be false. A theory in its day helps to solve the problems of the day.

It doesn't matter whether you're talking about bombs or the intelligence quotients of one race as against another if a man is a scientist, like me, he'll always say Publish and be damned.