The present study clearly distances itself from previous literature on the topic by demonstrating that Kant's theory of time cannot be understood without his theory of space and his critique of idealism. Karin Michel presents a reconstruction of Kant's proof of the genuine subjectivity of time. She takes account of both the form and the content of the proof, and also takes issue throughout with Kant commentators and critics. This clarifies not only Kant's radically new philosophical approach, but also the significance of the proof for his grand project of the critique of reason.