 Kant’s catalogue of virtues and vices is organized by his system of duties. These duties are grounded in the moral law, the supreme principle of morality, which impresses itself on us as a categorical imperative. All duties must ultimately derive from this supreme moral principle. But in the Metaphysics of Morals, Kant’s discussion of particular duties of virtue is based more directly on what he calls the “supreme principle of the doctrine of virtue”. This principle enjoins us to “act in accordance with a maxim of ends that it can be a universal law for everyone to have” (MM 6:395). As Kant explains,