Human beings are never to be treated as a means but always as ends.

He who is cruel to animals becomes hard also in his dealings with men. We can judge the heart of a man by his treatment of animals.

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.

An action is essentially good if the motive of the agent be good, regardless of the consequences.

There is nothing higher than reason.

Act so as to use humanity, yourself and others, always as an end and never as a means to an end.

Prudence reproaches; conscience accuses.