The dead govern the living.
The sacred formula of positivism: love as a principle, the order as a foundation, and progress as a goal.
Induction for deduction, with a view to construction.
Everything is relative; and only that is absolute.
In mathematics we find the primitive source of rationality; and to mathematics must the biologists resort for means to carry out their researches.
C'este donc par l'étude des mathématiques, et seulement par elle, que l'on peut se faire une idée juste et approfondie de ce que c'est qu'une science.