"Kritik der reinen Vernunft" by Immanuel Kant is a philosophical work published in 1781. Kant investigates the limits and scope of metaphysics by examining what reason can know independently of experience. He introduces groundbreaking ideas about space, time, and knowledge, challenging both rationalist and empiricist traditions. The central question: How can we have knowledge that is both necessary and adds to our understanding? This inquiry would reshape Western philosophy.