These essays are concerned with the overall nature of Kant's philosophical system, and thus with his deepest intentions and basic commitments. The first three essays deal with Kant's approach to things in themselves and with the realm of noumenal causality. The second part considers Kant's approach to the methodology of rational inquiry, and, in particular, his views on cognitive systematization and the limits of philosophizing itself. The third section focuses on the role played by the categorical imperative in both theoretical and practical philosophy. The aim throughout is to show that in an important sense Kant is prepared to assert the primacy of practical over theoretical philosophy.