"The Critique of Practical Reason" by Immanuel Kant is a philosophical work published in 1788. As the second of Kant's three critiques, it explores how pure reason can motivate moral action independent of sensory experience. The work establishes principles of morality, examines the concept of the highest good, and introduces the famous postulates of God's existence and the soul's immortality. Building on his earlier Groundwork, Kant places ethics within his broader critical philosophy, investigating how reason alone determines the will.