Kant's Critique of Pure Reason (1781) is the central text of modern philosophy. It brings together the two opposing schools of philosophy: rationalism, which grounds all our knowledge in reason, and empiricism, which traces all our knowledge to experience. The Critique is a profound and challenging investigation into the nature of human reason, establishing its truth and its falsities, its illusions and its reality. Reason, argues Kant, is the seat of all concepts, including God, freedom and immortality and must therefore precede and surpass human experience.