Dissent is the mark of freedom, as originality is the mark of independence of mind. … No one can be a scientist … if he does not have independence of observation and of thought.

The world today is made, it is powered by science; and for any man to abdicate an interest in science is to walk with open eyes towards slavery.

The basis for poetry and scientific discovery is the ability to comprehend the unlike in the like and the like in the unlike.

We are a scientific civilization. That means a civilization in which knowledge and its integrity are crucial. Science is only a Latin word for knowledge ... Knowledge is our destiny.

There are three creative ideas which, each in its turn, have been central to science. They are the idea of order, the idea of causes, and the idea of chance.

Beyond all our actions stands the larger shadow: How are we to choose between what we have been taught to think right and something else which manifestly succeeds?

Sex was invented as a biological instrument by (say) the green algae. But as an instrument in the ascent of man which is basic to his cultural evolution, it was invented by man himself.