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.

The eloquence of a scientist is clarity; scientific truth is always more luminous when its beauty is unadorned than when it is tricked out in the embellishments with which our imagination would seek to clothe it.

In teaching man, experimental science results in lessening his pride more and more by proving to him every day that primary causes, like the objective reality of things, will be hidden from him forever and that he can only know relations.

Priestley [said] that each discovery we make shows us many others that should be made.

Science does not permit exceptions.

Mediocre men often have the most acquired knowledge

Well-observed facts, though brought to light by passing theories, will never die; they are the material on which alone the house of science will at last be built.