Metaphysics of Morals

There is ... only a single categorical imperative and it is this: Act only on that maxim through which you can at the same time will that it should become a universal law.

Even if a civil society were to be dissolved by the consent of all its members (e.g., if a people inhabiting an island decided to separate and disperse throughout the world), the last murderer remaining in prison would first have to be executed, so that each has done to him what his deeds deserve and blood guilt does not cling to the people for not having insisted upon this punishment; for otherwise the people can be regarded as collaborators in his public violation of justice.

Der kategorische Imperativ, der überhaupt nur aussagt, was Verbindlichkeit sei, ist: handle nach einer Maxime, welche zugleich als ein allgemeines Gesetz gelten kann.

There is … only a single categorical imperative and it is this: Act only on that maxim through which you can at the same time will that it should become a universal law.

Wer sich aber zum Wurm macht, kann nachher nicht klagen, dass er mit Füßen getreten wird.

However, he who makes himself a worm cannot complain afterwards that he gets stepped on.

Human freedom is realised in the adoption of humanity as an end in itself, for the one thing that no-one can be compelled to do by another is to adopt a particular end.