"The elements of Realpolitik, exhaustively listed, are these: The ruler's, and later the state's, interest provides the spring of action; the necessities of policy arise from the unregulated competition of states; calculation based on these necessities can discover the policies that will best serve a state's interests; success is the ultimate test of policy, and success is defined as preserving and strengthening the state . Ever since Machiavelli, interest and necessity — and raison d'état, the phrase that comprehends them-have remained the key concepts of Realpolitik. From Machiavelli through Meinecke and Morgenthau the elements of the approach and the reasoning remain constant. Machiavelli stands so clearly as the exponent of Realpolitik that one easily slips into thinking that he developed the closely associated idea of balance of power as well . Although he did not, his conviction that politics can be explained in its own terms established the ground on which balance-of-power theory can be built."