Claude Bernard Quotes

[T]heories 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.

Leçons sur les Phénomènes de la Vie Communs aux Animaux et aux Végétaux.

Men who have excessive faith in their theories or ideas are not only ill prepared for making discoveries; they also make very poor observations.

A modern poet has characterized the personality of art and the impersonality of science as follows: Art is I: Science is We.

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

[I]t is important to determine at what point to apply doubt, so as to distinguish it from scepticism, and to show how scientific doubt becomes an element of the greatest certainty. The sceptic disbelieves in science and believes in himself; he believes enough in himself to dare deny science and to assert that it is not subject to definite, fixed laws. The doubter is a true man of science; he doubts only himself and his interpretations, but he believes in science; in the experimental sciences, he even accepts a criterion of absolute scientific principle.

Science does not permit exceptions.

[P]articular facts are never scientific; only generalization can establish science.

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

Science admits no exceptions; otherwise there would be no determinism in science, or rather, there would be no science.

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

Leçons sur les Phénomènes de la Vie Communs aux Animaux et aux Végétaux (1878-1879).

Considered in itself, the experimental method is nothing but reasoning by whose help we methodically submit our ideas to experience,—the experience of facts.

In sciences of observation, man observes and reasons experimentally, but he does not experiment; and in this sense we might say that a science of observation is a passive science. In sciences of experimentation, man observes, but in addition he acts on matter, analyzes its properties and to his own advantage brings about the appearance of phenomena which doubtless always occur according to natural laws, but in conditions which nature often has not yet achieved. With the help of these active experimental sciences, man becomes an inventor of phenomena, a real foreman of creation: and under this head we cannot set limits to the power that he may gain over nature through future progress in the experimental sciences.

The stability of the internal medium is a primary condition for the freedom and independence of certain living bodies in relation to the environment surrounding them.