Starting in Greece, for over twenty-three centuries, the ideal of Natural Law has been appealed to in Western moral and legal philosophy as a grounding for ethics, law, and jurisprudence, centered on capacities of a common “human nature.” From the early medieval rise of “Christendom,” it was embedded within a theistic and religious system for over a millennium, during which time it was treated as incomplete and part of an enveloping Divine Law requiring unconditional forgiveness and loving kindness even to strangers, enemies and the wicked. Modern agnosticism in theology, religion, and metaphysics then saw Natural Law distinguished from religion and these demands, but still suspect due to its lingering ties with religion. It endured through its meta-ethical capacity to present a stable theory of truth about being and “the highest good”, while the reference of that definite description varied; a theory of human nature’s capabilities and our wish for wellbeing; some common moral principles, precepts, and virtues as means to the common good; and a decision procedure for ethics.