Claude Bernard


French Physiologist

Author Quotes

Those who do not know the torment of the unknown cannot have the joy of discovery.

Well-observed facts, though brought to light by passing theories, will never die; they are the material on which alone the house of science will at last be built.

Feeling alone guides the mind and constitutes the primum movens of science. Genius is revealed in a delicate feeling which correctly foresees the laws of natural phenomena. But this we must never forget: the correctness of feeling and the fertility of an idea can be established and proved only by experiment.

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.

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

Priestley [said] that each discovery we make shows us many others that should be made.

The desire formulates the need; the hypothesis is the need for fact.

The minds that rise and become really great are never self-satisfied, but still continue to strive.

Those who have an excessive faith in their theories or in their ideas are not only poorly disposed to make discoveries, but they also make very poor observations.

What we now call an exception is a phenomenon, one or more of whose conditions are unknown. If the conditions of the phenomenon of which we speak were known and determined, there would be no further exceptions: medicine would be as free from them as any other science.

First causes are outside the realm of science.

In the organism, physiology is the executive branch; but the legislative branch is creation.

Man does not limit himself to seeing; he thinks and insists on learning the meaning of phenomena whose existence has been revealed to him by observation. So he reasons, compares facts, puts questions to them, and by the answers which he extracts, tests one by another. This sort of control, by means of reasoning and facts, is what constitutes experiment, properly speaking; and it is the only process that we have for teaching ourselves about the nature of things outside us.

Progress is achieved by exchanging our theories for new ones which go further than the old, until we find one based on a larger number of facts. ... Theories 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.

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

The opinions of other people are a stimulus to us, which arouses others (opinions) in us. It is essentially in this way that they (other people) serve us. .

To be worthy of the name, an experimenter must be at once theorist and practitioner. While he must completely master the art of establishing experimental facts, which are the materials of science, he must also clearly understand the scientific principles which guide his reasoning through the varied experimental study of natural phenomena. We cannot separate these two things: head and hand. An able hand, without a head to direct it, is a blind tool; the head is powerless without its executive hand.

When a physician is called to a patient, he should decide on the diagnosis, then the prognosis, and then the treatment. ... Physicians must know the evolution of the disease, its duration and gravity in order to predict its course and outcome. Here statistics intervene to guide physicians, by teaching them the proportion of mortal cases, and if observation has also shown that the successful and unsuccessful cases can be recognized by certain signs, then the prognosis is more certain.

Great men have been compared to giants, upon whose shoulders climb the pygmies - who nevertheless see further than they do.

In the patient who succumbed, the cause of death was evidently something which was not found in the patient who recovered; this something we must determine, and then we can act on the phenomena or recognize and foresee them accurately. But not by statistics shall we succeed in this; never have statistics taught anything, and never can they teach anything about the nature of the phenomenon.

Man is forced to be free for this reason alone; that he has a conscience and judgement. His liberty flows from this. He is free to do good or bad; but when he has done bad, remorse proves to him that he was free, and that he could have done otherwise, had he so wished.

Proof that a given condition always precedes or accompanies a phenomenon does not warrant concluding with certainty that a given condition is the immediate cause of that phenomenon. It must still be established that when this condition is removed, the phenomena will no longer appear.

The eloquence of a scientist is clarity; scientific truth is always more luminous when its beauty is unadorned than when it is tricked out in the embellishments with which our imagination would seek to clothe it.

The origin of an original work is always the pursuit of a fact which does not fit into accepted ideas.

Today no one says any longer 'it is good; that is fine'. No one believes in himself. He says it will sell - or it will not sell.

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French Physiologist