History shows that the danger threatening the independence of this or that nation has generally arisen, at least in part, out of the momentary predominance of a neighbouring State at once militarily powerful, economically efficient, and ambitious to extend its frontiers or spread its influence, the danger being directly proportionate to the degree of its power and efficiency, and to the spontaneity or ‘inevitableness’ of its ambitions. The only check on the abuse of political predominance derived from such a position has always consisted in the opposition of an equally formidable rival, or of a combination of several countries forming leagues of defence. The equilibrium established by such a grouping of forces is technically known as the balance of power, and it has become almost an historical truism to identify England's secular policy with the maintenance of this balance by throwing her weight now in this scale and now in that, but ever on the side opposed to the political dictatorship of the strongest single State or group at a given time.