Since several geometries are possible, is it certain ours is the true one? - Henri Poincaré

The Scientist must set in order. Science is built up with facts, as a house is with stones. But a collection of facts is no more a science than a heap of stones is a house.

Thought is only a flash between two long nights, but this flash is everything.

The task of the educator is to make the child's spirit pass again where its forefathers have gone, moving rapidly through certain stages but suppressing none of them. In this regard, the history of science must be our guide.