In this work, Kant explores nature of man's reason, knowledge, and illusion in a comprehensive and profound way. The book combines two competing philosophical doctrines: rationalism where all our knowledge is grounded in reason, and empiricism that attempts to build a bridge between our knowledge and experience. Kant's transcendental idealism suggests a third way that goes far beyond the above two options. Many people call Kant's Critique of Pure Reason the culmination of Western philosophy.