The concept of systematicity is central to Immanuel Kant's conception of scientific knowledge and to his practical philosophy. But Kant also held that we must be able to unite the separate systems of nature and freedom into a single system: on the one hand, morality itself requires that we be able to see its commands and goals as realizable within nature, while on the other hand our experience of nature itself leads us to see it as a system with the goal of human moral development. The essays in this volume, including two published here for the first time, explore various aspects of Kant's conception of the system of nature, the system of freedom, and the system of nature and freedom. The essays in the first part explore the systematicity of concepts and laws as the ultimate goal of natural science, consider the implications of Kant's account of our experience of organisms for the goal of the unity of science, and examine Kant's attempts to prove that the existence of an ether is a necessary condition for a physical system of nature. The essays in the second part explore Kant's view that morality requires a systematic union of persons as ends in themselves and of the ends that persons set for themselves, and examine the system of duties and obligations necessary to realize such a systematic union of persons and their ends. These essays thus examine both the general foundations of Kant's moral philosophy and his final account of the duties of right or justice and of ethics or virtue in his late work, the "Metaphysics of Morals". The essays in the third part examine Kant's attempt, in the last of his three great critiques, the "Critique of the Power of Judgment", to unify the systems of nature and freedom through a radical transformation of traditional teleology as a theory of the creation of organic nature into an account of our experience of organic nature and of nature as a whole.