As long as people believe in absurdities they will continue to commit atrocities.

The man visited by ecstasies and visions, who takes dreams for realities is an enthusiast; the man who supports his madness with murder is a fanatic.

Those who think are excessively few; and those few do not set themselves to disturb the world.

What is not in nature can never be true.

What would constitute useful history? That which should teach us our duties and our rights, without appearing to teach them.

Man is free at the instant he wants to be.

When we cannot use the compass of mathematics or the torch of experience...it is certain we cannot take a single step forward.