Jean Bodin. The first thinker who systematically expounded the theory of state sovereignty in history was the Spanish jurist Jean Bodin. The book Six Books on Land, State and Sovereignty clearly states that "sovereignty is an absolute, indivisible and unrestricted power", and the foundation of national sovereignty is "the authority of law". This concept has been widely spread in European political theory and practice, and has become the basis of international law and modern national sovereignty.