“To the infinite diversity of local liberties its will is to substitute regularity of institutions; political and administrative centralization.”[160] As Luchaire has elsewhere observed, the current everywhere “substituted, in the paths of administration, justice, and finance, the lay and burgher for the ecclesiastical and noble element.” In other words, the economic type steadily gained ground, and the process went on until the Revolution. Saint Simon never forgave Louis XIV. for surrounding himself with men of mean birth, dependent on his will. “The Duke of Beauvilliers was the single example in the whole course of his reign, as has been remarked in speaking of this duke, the only nobleman who was admitted into his council between the death of Cardinal Mazarin and his own; that is to say, during fifty-four years.”[161] From the middle of the twelfth to the middle of the thirteenth century was an interval of almost unparalleled commercial prosperity--a prosperity which is sufficiently proved by the sumptuous quality of the architecture of the time. Unquestionably the most magnificent buildings of modern Europe date from this period, and this prosperity was not limited to any country, but extended from Cairo to London. Such an expansion of trade would have been impossible without a corresponding expansion of the currency, and as no new mines were discovered, recourse was had to paper. By the year 1200 bills of exchange had been introduced,[162] and in order to give the bill of exchange its greatest circulating power, a system of banking was created which operated as a universal clearing house, and by means of which these bills were balanced against each other.