Claude Bernard Quotes

[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.

A contemporary poet has characterized this sense of the personality of art and of the impersonality of science in these words,—"Art is myself, science is ourselves."

[T]he experimental method draws from within itself an impersonal authority which dominates science. It forces this authority even on great men.[…] Every period has its own sum total of errors and of truths. Certain mistakes are, in a sense, inherent in their period, so that only the subsequent progress of science can reveal them.… [T]he further science advances, the more it takes an impersonal form and detaches itself from the past.

[T]hey make poor observations, because they choose among the results of their experiments only what suits their object, neglecting whatever is unrelated to it, and carefully setting aside everything which might tend toward the idea they wish to combat.

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

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.

[T]he science of life […] is a superb and dazzlingly lighted hall which may be reached only by passing through a long and ghastly kitchen.

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

The mental never influences the physical. It is always the physical that modifies the mental, and when we think that the mind is diseased, it is always an illusion.

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

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

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

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.

Leçons de Pathologie Expérimentale (1872).

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