What can we know? What should we do? What can we hope for? Best known for his Critique of Pure Reason, German thinker Immanuel Kant based his philosophy around these fundamental questions of human experience. His most intriguing writings are excerpted here, including his The Doctrine of Virtue, Critique of Practical Reason, The Moral Law, and other seminal works, each revealing the critical analysis that keeps Kant among the most influential of modern philosophers.