A discovery is generally an unforeseen relation not included in theory.

The doubter is a true man of science: he doubts only himself and his interpretations, but he believes in science.

We achieve more than we know. We know more than we understand. We understand more than we can explain.

Progress is achieved by exchanging our theories for new ones which go further than the old, until we find one based on a larger number of facts. ... Theories are only hypotheses, verified by more or less numerous facts. Those verified by the most facts are the best, but even then they are never final, never to be absolutely believed.

If I had to define life in a single phrase, I should clearly express my thought of throwing into relief one characteristic which, in my opinion, sharply differentiates biological science. I should say: life is creation.

We must never make experiments to confirm our ideas, but simply to control them.

Mediocre men often have the most acquired knowledge