tripped up and overthrown as soon as they stepped beyond the circle of conventional ideas. It will therefore suffice for our present purpose to state in the barest outline the leading events of international politics, and the chief advances in the theory of government, which signalised the Middle Ages. Extensive diplomatic combinations, though continually planned, seldom came to the birth and very rarely led to any notable result. The existence of some common interests was recognised; no power viewed with indifference any movement threatening the existence of the Papacy, which represented religious unity, or of the crusading principalities which formed the outer bulwark of Western Christendom; the principle of the Balance of Power, though not yet crystallised into a dogma, was so far understood that the inordinate growth of any single power alarmed the rest, even though they stood in no imminent danger of absorption. Therefore whenever the Empire gained the upper hand over the Church, whenever a new horde of Asiatics appeared on the horizon, whenever France seemed about to become a province of England, or Italy a province of France, the alarm was sounded by the publicists, and there ensued a general interchange of views between the monarchies; treaty was piled on treaty, alliance parried with alliance, as industriously as at any time in modern history. But the peoples seldom moved, and the agitation of the ruling classes effervesced in words. It is altogether exceptional to find two of the greater states uniting for the humiliation of a third, as England and the Empire united against Philip Augustus of France. Few medieval battles were so far-reaching in their consequences as Bouvines (1214), to which England owes her Magna Carta, Germany the magnificent and stormy autumn of the Hohenstauffen dynasty, France the consolidation of her long-divided provinces under an absolutist monarchy. At ordinary times there were in medieval Europe two groups of states with separate interests and types of polity. They were divided from one another by a broad belt of debatable territory, extending from Holland to the coast of Provence--the northern lands of the Carolingian Middle Kingdom.