Claude Bernard

Science does not permit exceptions.

Mediocre men often have the most acquired knowledge.

The true worth of an experimenter consists in his pursuing not only what he seeks in his experiment, but also what he did not seek.

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.

A fact in itself is nothing. It is valuable only for the idea attached to it, or for the proof which it furnishes.

Experimentation is an active science.