Descriptive anatomy is to physiology what geography is to history, and just as it is not enough to know the typography of a country to understand its history, so also it is not enough to know the anatomy of organs to understand their functions.

The experimenter who does not know what he is looking for will not understand what he finds.

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

Theories are like a stairway; by climbing, science widens its horizon more and more, because theories embody and necessarily include proportionately more facts as they advance.

A fact in itself is nothing. It is valuable only for the idea attached to it, or for the proof which it furnishes.

We must never make experiments to confirm our ideas, but simply to control them.

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