First causes are outside the realm of science.

The minds that rise and become really great are never self-satisfied, but still continue to strive.

A discovery is generally an unforeseen relation not included in theory.

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

Now, a living organism is nothing but a wonderful machine endowed with the most marvellous properties and set going by means of the most complex and delicate mechanism.

The stability of the internal medium is a primary condition for the freedom and independence of certain living bodies in relation to the environment surrounding them.

Proof that a given condition always precedes or accompanies a phenomenon does not warrant concluding with certainty that a given condition is the immediate cause of that phenomenon. It must still be established that when this condition is removed, the phenomen will no longer appear.