The Hapsburgs of Austria were not to be regarded as foreign conquerors of Belgium. From the outset they had claimed to be the natural heirs of the Hapsburgs of Spain, and that claim was admitted by France, England, and Holland, and by the States-General of the Belgian provinces. There could be no question of Austrian “domination.” In their relation to Belgium the Hapsburgs assumed the title of natural prince, as did Charles V at the beginning of the sixteenth century. Moreover, by the Treaty of the Barriers, Charles VI of Austria publicly proclaimed that his house assumed the rule over Belgium, subject to all the restrictions and guaranties to which the Hapsburgs of Spain had been subject. According to the treaties, Belgium was ceded to the Austrian Hapsburgs on condition that the predominance of the Catholic church in the country as well as the rights of the states and cities be recognized. The Catholic church and its position as the religion of the state were to be respected on account of the desire of France to erect a moral and religious barrier between herself and Protestant Holland; the popular rights were to be respected because the theory of the European balance of power required that the Emperor should be permitted only a limited sway. A strong, universal monarchy was no longer possible in Europe. The theory of the European balance of power had found expression through the Treaty of Westphalia (1648), whereby Europe ceased to be exclusively and officially Catholic, and Protestantism was granted recognition in law. Since the arbitration of the Pope in international matters was no longer possible, owing to the refusal of the Protestant powers to acknowledge his decisions, each country had to rely only upon itself. The weaker states had only one protection, therefore, namely, to unite against any power which might try to absorb them. Out of these principles grew the idea of the European balance of power, according to which no state was to be allowed to grow strong enough to menace the peace of the world. The external constitution of Belgium under Austrian rule having been established, Charles VI proceeded to protect the rights of his family in respect to internal conditions. As Charles V had established the principle of the indivisibility of the Spanish Netherlands by the Augsburg transaction, already mentioned, the new Emperor established the same principle for the “Austrian Netherlands” by a similar act, the “Pragmatic Sanction” of 1725. Belgium was forever to be kept as an indivisible whole, the eldest son to be heir to the throne, and the right of succession of the female descendants in case of the failure of a male heir was again admitted.