One cannot overestimate the contribution of the work of the Spanish Dominican Francisco de Vitoria (1483-1546) for the understanding and interpretation of the theology and philosophy of the Early Modern era. Vitoria’s main point of reference was the ›Summa Theologiae‹ of Thomas Aquinas, whose analysis of ethical, juridical, and political questions (with reference to Aristotle’s philosophy) formed the basis for Vitoria’s broad discussion of problems we also face today. The treatise ›De lege‹ (›About the Law‹) explains the rationality of natural law, encourages the emancipation of civil law from ecclesiastical law, and calls for the submission also of the legislator to the law as well as the principle of publicness. These are all elements of a doctrine which has been fundamental for several generations of theologians, jurists, and philosophers.