METAPHYSIC OF MORALS Just as pure mathematics are distinguished from applied, pure logic from applied, so if we choose we may also distinguish pure philosophy of morals (metaphysic) from applied (viz., applied to human nature). By this designation we are also at once reminded that moral principles are not based on properties of human nature, but must subsist a priori of themselves, while from such principles practical rules must be capable of being deduced for every rational nature, and accordingly for that of man.