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

[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.

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

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