In the second book of ›De legibus ac Deo legislatore‹ (1612), the summa of his theology of law, Francisco Suárez (1548–1617) explains and develops his concept of eternal and natural law as well of international law. Suárez manages a critical revision of the theories of eternal law that have been presented by Augustine and Thomas Aquinas and thus a progressive development of medieval theology of law. Concerning the natural and international law debate that will be intensified by Hugo Grotius and Thomas Hobbes and held controversial to Christian Wolff, Suárez already formulates genuine conceptions that promote the early modern development of political theory until the 18th century.