Immanuel Kant (born Emanuel Kant; 22 April 1724 – 12 February 1804) was a German philosopher. Born in Königsberg in the Kingdom of Prussia, he is considered one of the central thinkers of the Enlightenment. His comprehensive and systematic works in epistemology, metaphysics, logic, ethics, aesthetics, political theory, and the philosophy of religion have made him one of the most influential and highly discussed figures in modern Western philosophy. Kant's philosophy is centered on the human subject and motivated by the desire to secure the possibility of both knowledge and morality against the threats of skepticism and determinism. In the Critique of Pure Reason (1781/1787), Kant argues for transcendental idealism, the doctrine that space and time are mere "forms of intuition" (German: Anschauung) that structure all experience and that we have knowledge only of "appearances" and not of the nature of things in themselves.