" Human nature, in which the laws of politics have their roots, has not changed since the classical philosophies of China, India, and Greece endeavored to discover these laws. Hence, novelty is not necessarily a virtue in political theory, nor is old age a defect. The fact that a theory of politics, if there be such a theory, has never been heard of before tends to create a presumption against, rather than in favor of, its soundness. Conversely, the fact that a theory of politics was developed hundreds or even thousands of years ago - as was the theory of the balance of power - does not create a presumption that it must be outmoded and obsolete. A theory of politics must be subjected to the dual test of reason and experience. To dismiss such a theory because it had its flowering in centuries past is to present not a rational argument but a modernistic prejudice that takes for granted the superiority of the present over the past. To dispose of the revival of such a theory as a "fashion" or "fad" is tantamount to assuming that in matters political we can have opinions but no truths. "
― Hans J. Morgenthau , Politics Among Nations