As early as 1953 he was complaining to Walter Lippmann about his “isolation from the center of affairs.” To Robert Hutchins, the president of the University of Chicago, he wrote, “There is virtually no possibility for a friendly critic of American foreign policy, such as myself, to make his voice heard by the educated American public.” He stood on the outside of Lyndon Johnson’s tent, though not by choice. The most influential magazine in his field, Foreign Affairs, was closed to him, refusing to publish his iconoclastic realpolitik pieces. Astoundingly, the publication’s longtime editor, Hamilton Fish Armstrong, called Morgenthau an “isolationist,” as well as “a propagandist and publicity seeker.” “The writer who speaks neither for the Establishment nor for any faction opposing it,” Morgenthau observed on the basis of painful experience, “has a hard time in placing what he writes.”

Whereas Kissinger knew how to seduce, Morgenthau was always forthright and outspoken, which was not the way to get ahead in Washington. Once he declared his opposition to American intervention in Vietnam and aired his unorthodox views about Communism, he became persona non grata in policymaking circles. And as the war in Vietnam ground on, he was brought close to despair over his powerlessness. “For those who have made it their business in life to speak truth to power, there is nothing left but to continue so to speak,” he wrote with bitterness in 1970, but “certainly with less confidence that it will in the short run make much of a difference in the affairs of man.” At his lowest, he came close to doubting the importance of reason itself. “The great issues of our day are not susceptible to rational solutions within the existing system of power relations.”

It would hardly have been surprising if Morgenthau, like so many others, had resented Kissinger, not only for his success but also for the fact that his success had been achieved through the kind of dissembling and calculated ambiguity that did not come naturally to Morgenthau. Yet that wasn’t Morgenthau’s reaction. Kissinger, he said approvingly, was a “first-rate scholar” who was able to acquire and hold “great power with the same brilliance.” To be sure, Morgenthau acknowledged that Kissinger did “very little that was not oriented toward . . . his personal power,” but personal advancement wasn’t necessarily a bad thing in his mind, and he admired Kissinger’s ability to operate successfully in the toxic, backstabbing environment that was the nation’s capital. Kissinger was no ordinary intellectual, helpless in the corridors of power. He knew how to adapt to the exigencies of politics. “Inevitably,” Morgenthau wrote, “if your ambition is not limited to scholarship but extends to the political sphere, you have to trim your sails to the prevailing winds.” Kissinger, he said, had trimmed his sails, but with “sagacity and decency,” and he reproached envious academics who saw nothing but opportunism and careerism. Much of the criticism of Kissinger, he insisted, was “unabashedly self-serving.”

Morgenthau never forgot a comment President Kennedy had once made to him after he had written something critical about the administration. “You should sit where I do,” Kennedy said to him. “He had a point,” Morgenthau conceded, and he went on to write thoughtful essays on the ways in which intellectuals and politicians both overlapped and differed, and about the hopeless complexities of “the collaboration problem.”

Intellectuals were important to policymaking, providing concepts and perspective, but they operated on the basis of different values from politicians. Scholars engaged with ideas; their aim was to be as intelligent as they could, and to present their arguments cogently. Statesmen had different goals. “The intellectual seeks truth,” Morgenthau said, “the politician power.” But Morgenthau was quick to add that this difference did not make the intellectual superior to the politician because power was an inescapable reality while the abstruse pursuit of truth carried burdens of its own. The politician was obliged to deal with facts, not theories, and facts had a tendency to “make mincemeat of the wrong ideas.” Intellectuals could be very smart without necessarily being especially wise, or even wise at all. The politician required “practical wisdom,” whereas the scholar or intellectual “may be intelligent without being wise in the ways of the world.”

Unlike the intellectual, the statesman or politician could not afford to operate from a position of absolutes. The real world was contradictory, unpredictable, tragic. Morgenthau was fond of a comment of Goethe’s “that the one who acts is always unjust and that nobody has justice but the one who observes.” Morgenthau came to amend this bleak thought, especially after his experience with the Vietnam War, insisting that there must be at least “an element of justice” in “the one who acts,” though he continued to believe that a straightforward or naïve commitment to justice in the world of facts was foolhardy at best. Ethical adjustments were always demanded by the real world. Two qualities, he said, were essential to the statesman: a sense of limits and “a commitment to a grand design,” which gave his policies an overall purpose. Intellectuals did not necessarily possess either of these qualities, and the ability to combine intellectuality and power was rare indeed. Morgenthau cited two examples from American history: the Founding Fathers and Abraham Lincoln. Henry Kissinger, apparently, was a third. Morgenthau wasn’t saying that Kissinger achieved the level of a Jefferson or Lincoln, but he did believe that Kissinger was a great statesman, one of the very greatest the United States had ever known. When their mutual friend John Stoessinger wrote a book-length apologia of Kissinger’s policies, Morgenthau called it “by far the best book written about Henry Kissinger.”

CONFRONTED WITH the intimidating realities of power, Morgenthau said, the intellectual could choose among four possible courses. He could retreat into an ivory tower to preserve his “purity” (as well as his self-righteousness). He could, as an alternative, adopt a position of “prophetic confrontation” in opposition to government policy. The first of these attained virtue of a cloistered sort, but only by denying power altogether. The second performed a traditional task of the intellectual, which was to speak truth to power, but it risked the danger of impracticality (“you should sit where I do”), along with its own form of sanctimoniousness. Once the Vietnam War heated up, Morgenthau was thrust into the second position, though it wasn’t what he wanted or expected for himself.

The other two courses accepted power, even cooperated with it, but in very different ways. The third path for the intellectual was to surrender his independence and in an act of cowardice become a propagandist for authority—or, to employ Kissinger’s framework, to yield to bureaucratic demands by just following orders and becoming a cog in the machine. Morgenthau was all too aware of the cowardice of intellectuals, not only from his days in Weimar Germany but also from his lonely opposition to Vietnam. Some supporters of the war, he wrote, “have attacked their dissenting colleagues with unaccustomed violence and with arguments as tortuous and inconsistent as to be inexplicable on purely intellectual grounds.” These scholars had ceased to be intellectuals and turned themselves into ideologues, tools of mere force, and at their worst they applied their intelligence to providing rationales for the state’s brute coercions.

Morgenthau’s fourth course, perhaps the most difficult, was to “enter the political process as an expert,” hoping to influence policy with the intellectual’s conceptual apparatus, but accepting the restrictions with which officials were obliged to operate. The result could never be entirely satisfying because compromises with one’s theories were always necessary, sometimes painful. Policies “are bound to fall short of the logical consistency and theoretical purity that are the earmarks of the intellectual detached from action.” The best that the intellectual in government could do to maintain his integrity was to try to put truth to the service of power, understanding that even if the achievement of perfect justice was never possible, he could still provide practical advice about the uses of power for legitimate ends. For instance, politicians could be helped to avoid yielding to the constant temptation to substitute power for reason instead of joining the two, or advised on how much power was required for the situation at hand, avoiding the excesses that came all too easily to the wielders of military might. It was the job of the intellectual in the White House to remind the president “of the brittleness of power, of its arrogance and blindness, of its limits and pitfalls.” For the intellectual to lose sight of truth was to capitulate to power instead of serving it.

But with all the inevitable compromises and adjustments to reality, how was it possible to know if one had made so many concessions as to become a mere tool of power? It was, Morgenthau said, “only a small step” to the intellectual bankruptcy of capitulation. His answer seems to have been that there is no definitive answer to this eternal question, no moral formula one could rely on. In a world without absolutes, each individual had to be judged according to the circumstances of his particular situation, and for this reason, the historian had more to teach about statesmanship than the quantifying social scientist.