Immanuel Kant was an 18th-century philosopher from Königsberg, Prussia (now Kaliningrad, Russia). He's regarded as one of the most influential thinkers of modern Europe & of the late Enlightenment. His most important work is The Critique of Pure Reason, an investigation of reason itself. It encompasses an attack on traditional metaphysics & epistemology, & highlights his own contribution to these areas. Other main works of his maturity are The Critique of Practical Reason, which is about ethics, & The Critique of Judgment, about esthetics & teleology.