Commentators on the work of Immanuel Kant have long held that his later "critical" writings are a radical rejection of his earlier, less celebrated efforts. This work demonstrates not only the developmental unity of Kant's individual writings, but also the unity of his work and life experience. The author argues that the central animating issues of Kant's lifework concerned the perplexing relation of spirit to body. Through an analysis of individual writings Shell maps the philosophical contours of Kant's early intellectual struggles and their relation to his more mature thought. The paradox of mind in matter and the tensions it generates - between freedom and determinacy, independence and community, ideal and real - are shown to inform the whole of his work. The author's critique goes further to consider the context of contemporary intellectual life. She explores the fascinating realm of Kant's sexual and medical idiosyncracies, linking them to the primary concerns of his critical philosophy. The work develops a treatment of the connection between Kant's philosophy and his chronic hypochondria, and illuminates connections in a remarkable convergence of life and thought, with theoretical and practical implications for modern times.