We must keep our freedom of mind, ... and must believe that in nature what is absurd, according to our theories, is not always impossible.

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

But while I accept specialization in the practice, I reject it utterly in the theory of science.

The goal of scientific physicians in their own science ... is to reduce the indeterminate. Statistics therefore apply only to cases in which the cause of the facts observed is still indeterminate.

Real science exists, then, only from the moment when a phenomenon is accurately defined as to its nature and rigorously determined in relation to its material conditions, that is, when its law is known. Before that, we have only groping and empiricism.

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

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