The modern political philosophy hasn’t recognized the limit of politics; it always easily falls into the trap of political romanticism and political nihilism. In contrast, Strauss adhering to the wisdom of classical political philosophy, tells us that the political life has some limits which human reason can’t exceed: the highest upper limit of political life is the rule of philosophy’s king, which is desirable, but not impossible; the lowest limit of political life is natural right principle, which is indispensable root of any political society. On the basis of this vision, the key of actual political practice is the balance of wisdom and agreement, and this is the fundamental spirit of classical political conservatism.