Julian Wuerth offers a radically new interpretation of Kant's theories of mind, action, and ethics. As the author of a Copernican turn in philosophy, Kant places the mind at the center of his philosophy, and yet his theory of the mind remains an enigma. Wuerth begins with a revolutionary new interpretation of this theory of mind. This new interpretation considers a far wider range of Kant's recorded thought from across his philosophical corpus than previous interpretations and advances in tandem with an interpretation of the foundations of Kant's transcendental idealism and his metaphysics of substance. Against traditional empiricist approaches, Wuerth demonstrates that Kant argues that we are conscious of our own noumenal substantiality and simplicity. But against rational psychologists, Kant draws on the teachings of his transcendental idealism to strip the conclusions of our noumenal substantiality and simplicity of their 'usefulness.' In the Paralogisms and elsewhere, Kant thus argues that we are not licensed to conclude our substantiality and simplicity in a sense that entails our permanence, our incorruptibility, or our immortality. Wuerth goes on to undertake a ground-breaking study of Kant's notoriously vast, complex, and opaque account of the mind's powers, and argues that Kant structures his system of philosophy on this system of the mind's powers. He next confronts the persisting stumbling block of interpretations of Kant's ethics—Kant's theory of action—and shows that Kant rejects intellectualist theories of action that reduce practical agents to pure reason. He argues that Kant's practical agent is shown to exercise a power of choice, or Willkür, subject to two irreducible conative currencies: moral motives and sensible incentives. While our intellectual nature provides us with insight into morality and in turn with moral motives, our sensible nature provides us with distinct-in-kind sensible incentives. Immoral choices at odds with the former can thus nonetheless be coherent choices in harmony with the latter. Finally, Wuerth applies these new findings about Kant's theory of mind and action to an analysis of the foundations of Kant's ethics. He rejects the dominant constructivist interpretation in favor of a moral realist one. At the heart of Kant's Enlightenment ethics is his insistence that the authority of a moral law rests in our recognition of its truth, not in an alleged commitment unfettered by truth. Kant guides us to clarity regarding the moral law, across his writings and across his various formulations of the moral law, using a single elimination of sensibility process that rejects the pretences of sensibility to isolate reason and its insights into moral right and wrong. Because moral authority issues from the cognition of pure practical reason and because sensibility can present coherent alternatives to moral choice, moral virtue requires more than mere clarity in cognition. Kant instead recognizes the centrality to moral living of the ongoing cultivation of our capacities more broadly, including our capacities for cognition, feeling, desire, and character.