“Critique of Pure Reason” is the foundational philosophical work by Immanuel Kant, first published in 1781. In this work, Kant investigates the limits and possibilities of human knowledge, develops the concept of transcendental idealism, and analyzes the a priori forms of sensibility and understanding. The book is considered one of the most important works in the history of Western philosophy, having exerted enormous influence on the development of epistemology and metaphysics.