The world, unfortunately, rarely matches our hopes and consistently refuses to behave in a reasonable manner.

Can I pay any higher tribute to a man [George Gaylord Simpson] than to state that his work both established a profession and sowed the seeds for its own revision? If Simpson had reached final truth, he either would have been a priest or would have chosen a dull profession. The history of life cannot be a dull profession.

Without a commitment to science and rationality in its proper domain, there can be no solution to the problems that engulf us. Still, the Yahoos never rest.

Nothing is more dangerous than a dogmatic worldview.

A man does not attain the status of Galileo merely because he is persecuted; he must also be right.

The world is full of signals that we don't perceive.

The causes of life's history [cannot] resolve the riddle of life's meaning.