To know how to wonder and question is the first step of the mind toward discovery.

It is not the germs we need worry about. It is our inner terrain.

The role of the infinitely small in nature is infinitely great.

Imagination should give wings to our thoughts but we always need decisive experimental proof, and when the moment comes to draw conclusions and to interpret the gathered observations, imagination must be checked and documented by the factual results of the experiment.

If you suppress laboratories, physical science will be stricken with barrenness and death.

The greatest derangement of the mind is to believe in something because one wishes it to be so.

There is no such thing as applied science, only the application of pure science.