of ethics (the doctrine of virtue) is: �Act on a maxim, the ends of which are such as it might be a universal law for everyone to have.� On this principle a man is an end to himself as well as others, and it is not enough that he is not permitted to use either himself or others merely as means (which would imply that be might be indifferent to them), but it is in itself a duty of every man to make mankind in general his end.

The principle of ethics being a categorical imperative does not admit of proof, but it admits of a justification from principles of pure practical reason. Whatever in relation to mankind, to oneself, and others, can be an end, that is an end for pure practical reason: for this is a faculty of assigning ends in general; and to be indifferent to them, that is, to take no interest in them, is a