The great experimental ...

The great experimental principle, then, is doubt, that philosophic doubt which leaves to the mind its freedom and initiative, and from which the virtues most valuable to investigators in physiology and medicine are derived.
The great experimental principle, then, is doubt, that philosophic doubt which leaves to the mind its freedom and initiative, and from which the virtues most valuable to investigators in physiology and medicine are derived.
 Claude Bernard

More phrases

Being self-made is a state of mind, and once you put that mentality to work, your success will come.
 Dave East
A lot of people change for good. Some people just fall off. Just trying to progress in anything, no matter what you're doing, I feel like any progression you make... some people aren't gonna be around you that were around you.
 Dave East
What a distressing contrast there is between the radiant intelligence of the child and the feeble mentality of the average adult.
Don't settle in the land of barely enough. That is where you are, it is not who you are. That's your location, it's not your identity. No matter what it looks like, have an abundant mentality.
Everything in your life, every experience, every relationship is a mirror of the mental pattern that is going on inside of you.

Quotes from the same author

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.
 Claude Bernard
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.
 Claude Bernard
Even mistaken hypotheses and theories are of use in leading to discoveries. This remark is true in all the sciences. The alchemists founded chemistry by pursuing chimerical problems and theories which are false. In physical science, which is more advanced than biology, we might still cite men of science who make great discoveries by relying on false theories.
 Claude Bernard
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.
 Claude Bernard
It is impossible to devise an experiment without a preconceived idea; devising an experiment, we said, is putting a question; we never conceive a question without an idea which invites an answer. I consider it, therefore, an absolute principle that experiments must always be devised in view of a preconceived idea, no matter if the idea be not very clear nor very well defined.
 Claude Bernard