The second of Kant's three critiques, Critique of Practical Reason forms the center of Kantian philosophy. Published in 1788, it expands upon the central themes of Kant's school of thought with a vigorous defense of Christianity that positively affirms the soul's immortality and the existence of God. This seminal text in the history of moral philosophy offers the most complete statement of Kant's theory of free will and a full development of his practical metaphysics.