Claude Bernard

[S]cience, in humbling our pride, proportionately increases our power.

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

If I had to define life in a word, it would be: Life is creation.

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

[A] living organism is nothing but a wonderful machine.

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

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

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.

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."

Our language, in fact, is only approximate, and even in science it is so indefinite that if we lose sight of phenomena and cling to words, we are speedily outside of reality.… [W]e must always cling to phenomena and see in words only expressions empty of meaning, if the phenomena they represent are not definite, or if they are absent.

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.

A great surgeon performs operations for stone by a single method; later he makes a statistical summary of deaths and recoveries, and he concludes from these statistics that the mortality law for this operation is two out of five. Well, I say that this ratio means literally nothing scientifically and gives us no certainty in performing the next operation; for we do not know whether the next case will be among the recoveries or the deaths. What really should be done, instead of gathering facts empirically, is to study them more accurately, each in its special determinism. We must study cases of death with great care and try to discover in them the cause of mortal accidents so as to master the cause and avoid the accidents.

[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.

[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.

True science teaches us to doubt and to abstain from ignorance.