The terrain is everything; the germ is nothing.

The investigator should have a robust faith - and yet not believe.

Effects vary with the conditions which bring them to pass, but laws do not vary. Physiological and pathological states are ruled by the same forces; they differ only because of the special conditions under which the vital laws manifest themselves.

I do not ... reject the use of statistics in medicine, but I condemn not trying to get beyond them and believing in statistics as the foundation of medical science. ... Statistics ... apply only to cases in which the cause of the facts observed is still [uncertain or] indeterminate. ... There will always be some indeterminism ... in all the sciences, and more in medicine than in any other. But man's intellectual conquest consists in lessening and driving back indeterminism in proportion as he gains ground for determinism by the help of the experimental method.

A man of science rises ever, in seeking truth; and if he never finds it in its wholeness, he discovers nevertheless very significant fragments; and these fragments of universal truth are precisely what constitutes science.

If I had to define life in a single phrase, I should clearly express my thought of throwing into relief one characteristic which, in my opinion, sharply differentiates biological science. I should say: life is creation.

True science teaches us to doubt and, in ignorance, to refrain.