The investigator should have a robust faith - and yet not believe.

Put off your imagination, as you put off your overcoat, when you enter the laboratory. Put it on again, as you put on your overcoat, when you leave.

Mediocre men often have the most acquired knowledge.

It is what we know already that often prevents us from learning.

Art is I science is we.

Observation is a passive science, experimentation an active science.

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.

Experimentation is an active science.

Science does not permit exceptions.