 A few additional differences are worth noting. First, unlike Hume, Kant insists on the unitary nature of virtue: “in its Idea (objectively) there is only one virtue (as moral strength of one’s maxims)” (MM 6:447; cf. MM 6:395 and 406). Second, Hume maintains that the concepts of virtue and vice can apply to things outside our control, such as traits and motives that spring involuntarily from our basic temperament. For example, wit, good memory, and other “mental abilities” are virtues because of their power to garner the approval of a judicious spectator, even if they spring from temperament, upbringing, or other factors outside the agent’s control (T 3.3.4.1–5). Kant, by contrast, restricts the application of virtue concepts to traits, behaviors, and attitudes that are voluntarily adopted and cultivated as a matter of principle. Each virtue and each vice has its own maxim (MM 6:404). For example, being “naturally” witty is not virtuous; neither is cultivating wit for the sake of social status or power. For Kant, wittiness is not an ethical virtue unless it is voluntarily cultivated for morally admirable reasons. Third, Kant and Hume view justice quite differently. Justice is central to Hume’s picture of morality, but Kant does not treat it as an ethical virtue at all. For Kant, justice is a matter of right or law (Recht), which regulates actions but not their underlying motives and ends. Furthermore, Hume treats justice as an “artificial” virtue, but Kant would reject the artificial-natural distinction altogether. On his view, ethical virtues are neither artificial nor natural in Hume’s sense. Finally, their conceptions of moral vice are quite different. For Hume a vice is a mental quality that provokes disapproval from a judicious spectator. A person’s vices do not necessarily say anything about the quality of her will as a whole or her fundamental attitude toward the demands of morality. But Kant holds that vice is a propensity to act contrary to the moral law (Rel 6:37), and it implies a genuine “contempt for moral laws” (C 27:463). As he puts it, “it is when an intentional transgression has become a principle that it is properly called a vice” (MM 6:390).