History of International Law Since the Peace of Westphalia
The treaties of Münster and Osnabrück gave to Europe a sort of international constitution which remained the basis of its public law down to the French Revolution. But it would be a serious error to assume that the international community of states as revealed to the world by the Peace of Westphalia implied the recognition of the science of international law as understood and practiced by the society of nations at the present time. The science of international law as it exists today is a result of slow historical growth and is the product of two main factors, viz., certain theories or principles on the one hand, and international practice or custom on the other. The relative value and influence of the contributions of each of these factors is so difficult to determine that they have never been thoroughly eifted or separated — a task left for the future historians of international law.