All children are essentially criminal.

I picture the vast realm of the sciences as an immense landscape scattered with patches of dark and light. The goal towards which we must work is either to extend the boundaries of the patches of light, or to increase their number. One of these tasks falls to the creative genius; the other requires a sort of sagacity combined with perfectionism.

I have only a small flickering light to guide me in the darkness of a thick forest. Up comes a theologian and blows it out.

Does not vanity itself cease to be blamable, is it not even ennobled, when it is directed to laudable objects, when it confines itself to prompting us to great and generous actions?

If there are one hundred thousand damned souls for one saved soul, the devil has always the advantage without having given up his son to death.

A thing is not proved because no one has ever questioned it... Skepticism is the first step toward truth.

The arbitrary rule of a just and enlightened prince is always bad. His virtues are the most dangerous and the surest form of seduction: they lull a people imperceptibly into the habit of loving, respecting, and serving his successor, whoever that successor may be, no matter how wicked or stupid.