Claude Bernard

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

“The science of life is a superb and dazzlingly lighted hall which may be reached only by passing through a long and ghastly kitchen.”

“A hypothesis is an idea which is submitted to the control of the experiment.”

“The stability of the internal environment is a primary condition for the freedom and independence of certain living bodies.”

“The experimenter who does not know what he is looking for will not understand what he finds.”

“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.”

“All the vital mechanisms, varied as they are, have only one object, that of preserving constant the conditions of life in the internal environment.”

“The constancy of the internal environment is the condition for a free and independent life.”

“Observation is a passive science, experimentation is an active science.”

“Put off your imagination, as you take off your overcoat, when you enter the laboratory.”

“In the experimental sciences, all progress is measured by the perfection of the means of investigation.”

“Art is 'I'; science is 'We'.”

“Those who have an excessive faith in their ideas are not well fitted to make discoveries.”

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

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

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

“When we meet a fact which contradicts a prevailing theory, we must accept the fact and abandon the theory, even when the theory is supported by great names and generally accepted.”

“Man can learn nothing unless he proceeds from the known to the unknown.”