The wise man can change his mind; the stubborn one, never.

Man must be disciplined, for he is by nature raw and wild.

Law And Freedom without Violence (Anarchy) Law And Violence without Freedom (Despotism) Violence without Freedom And Law (Barbarism) Violence with Freedom And Law (Republic)

Metaphysics is a dark ocean without shores or lighthouse, strewn with many a philosophic wreck.

The sceptics, a kind of nomads, despising all settled culture of the land, broke up from time to time all civil society. Fortunately their number was small, and they could not prevent the old settlers from returning to cultivate the ground afresh, though without any fixed plan or agreement.

Enlightenment is man's leaving his self-caused immaturity. Immaturity is the incapacity to use one's intelligence without the guidance of another. Such immaturity is self-caused if it is not caused by lack of intelligence, but by lack of determination and courage to use one's intelligence without being guided by another. Sapere Aude! Have the courage to use your own intelligence! is therefore the motto of the enlightenment.

An action, to have moral worth, must be done from duty.