What is Morality? There is a saying, “manners maketh the man,” that rings true on a fundamental level, and philosophers have attempted to answer the question, “what maketh manners” since the dawn of civilization. In this book, the philosopher, Immanuel Kant, explains the fundamental metaphysical laws governing moral experience. He argues that these laws are metaphysical in that they can be discerned "a priori" — that is, by the exercise of pure reason and without external reference. Fundamentals of the Metaphysics of Morality laid the foundation for Kant's Magnum Opus, The Critique of Pure Reason, and develops an idea which would become central to his ethical philosophy. This idea is that of the categorical imperative. This moral maxim holds several points to be self-evident, namely, that morality is intertwined with the fabric of metaphysical reality. Simply stated: Act only when you can will that such action should become a Universal Law for all mankind.