Immanuel Kant is the greatest philosopher of Western Europe, one of the leading thinkers of the Enlightenment era, the founder of German classical philosophy, and the creator of critical idealism, who made a decisive contribution to the development of the European philosophical tradition. “Critique of Practical Reason” is Kant’s main ethical treatise, developing the ideas of his “Critique of Pure Reason” and exploring in detail the concept of the categorical imperative—the highest principle of morality.