IN THE late 1940s, Leo Strauss left the New School for Social Research in New York to take a position at the University of Chicago. Hans Morgenthau, who was a professor in the Political Science Department and on his way to establishing himself as the father of realism, was instrumental in securing the post for Strauss, and the two men, whose life experiences were so very similar, immediately formed a close bond. Morgenthau told an associate that he learned more from Strauss “in a few minutes’ conversation than from hours with other political scientists.” Strauss was equally admiring of Morgenthau. Yet that initial compatibility masked deeper incompatibilities—both in outlook and personality—that weren’t long in coming to the surface and scotched whatever element of sympathy existed between the two men.

Some years later, Hannah Arendt came to Chicago. She and Strauss never got along (though they had known each other since their student days in Germany when, it is said, Strauss courted her). But her relationship to Morgenthau was very different, and also very different from Strauss’s relationship to Morgenthau. In contrast to the Strauss-Morgenthau connection, there always remained a quality of sympathy between Arendt and Morgenthau—colored, it should be said, by an element of the erotic.

The two met in the early 1950s, and developed an unshakable friendship that lasted up to Arendt’s death in 1975. Hans Jonas, who had known her in Germany during the 1920s and who saw her every day when they attended the University of Marburg, remembered that “it was almost to be taken for granted that men of high intelligence and sensibility would be enchanted by Hannah.” Morgenthau was enchanted. “What struck one at first meeting Hannah Arendt,” he recalled, was “the vitality of her mind, quick—sometimes too quick—sparkling, seeking, and finding hidden meanings and connections beneath the surface of man and things.” She had an extraordinary depth of knowledge combined with rare intellectual passion. “As others enjoy playing cards or the horses for their own sake, so Hannah Arendt enjoyed thinking.”

On another occasion, Morgenthau likened her manner of thinking to poetry:

If you consider the enormous suggestiveness of her insights into political matters...you realize that her mind worked in a way not dissimilar to the poetic mind, which creates affinities, which discovers relationships that appear obvious once they are formulated but that nobody had thought of before the poet formulated them.

And in an expression of grievous sorrow at her death, he said: “I am left with an unutterable regret.”

ARENDT HAS been described as Morgenthau’s “intellectual companion,” and through the decades of their friendship, each supported the other in good times and bad. There was no more trying period for Arendt than the months in the mid-1960s when the controversy over her book Eichmann in Jerusalem was burning white-hot. Along with Mary McCarthy and Karl Jaspers, Morgenthau was unfailingly loyal. He dined with her at the University of Chicago faculty club when other faculty members made a point of shunning her, and when she was attacked in the New York Times, he wrote a letter to the editor in her defense. Reporting from New York, where a public meeting to discuss her ideas on Eichmann quickly deteriorated into a shouting match, Morgenthau said: “The Jewish community is up in arms.” He continued, “Reality has protruded into the protective armor of illusion and the result is psychological havoc.” For her part, Arendt was there for him when he was suffering through a series of illnesses. And when he was in danger of damaging his professional reputation because of his opposition to the Vietnam War, she was by his side.

Over the years, they celebrated New Year’s, watched the funeral of John F. Kennedy, even vacationed together—though on one trip, Morgenthau may have made the not-uncommon discovery that even the dearest friends sometimes do not make good traveling companions. “She can be a real pain in the neck,” he wrote in a letter home. On a list of the ten books that mattered most to him that he compiled in 1976, Morgenthau included Arendt’s The Human Condition. Late in life, Morgenthau even proposed marriage. According to her biographer, Arendt was “disconcerted,” but she was hardly unaccustomed to male attention and knew how to handle a delicate situation. A psychoanalyst who was close to Morgenthau in his later years took a somewhat different view: “My hunch is that each of them thought it would solve many problems if they were able to love the other, but neither one did or could, yet each believed himself (herself) to be loved and desired by the other.” The relationship survived her rejection and they continued to enjoy each other’s company, as well as their wide-ranging discussions. (What if they had wed? One pictures a younger Henry Kissinger, who considered Morgenthau his mentor, as a dinner guest, conversing animatedly with Morgenthau about the events of the day while Arendt looked on severely, mentally dissecting the arguments of both men.) Arendt had been involved in the planning of a testimonial volume to Morgenthau in the 1970s, and had been commissioned to write the concluding essay, but she died before she could take up the assignment.

Intellectually, they were very close. Like Morgenthau’s, Arendt’s work was a rebuke to the quantifiers who dominated American political thought. The Princeton political scientist Sheldon S. Wolin said Arendt “occupies a special place in the recent history of political theory” because she understood the importance of ideas and rescued theory from “the dreary and trivial categories of academic political science.” Philosophical works like Arendt’s The Human Condition “came as a deliverance,” Wolin said, permitting discussion once again of large and challenging concepts like freedom, action, judgment and human happiness. And as with Morgenthau, her thinking, Wolin observed, “led toward a radical pessimism.” (Among most professional philosophers in the United States at the time, the common view was that whatever it was Arendt was doing, it wasn’t philosophy.)

POLITICALLY, TOO, Morgenthau and Arendt tended to see eye to eye. Though both were fierce anti-Communists, they were united in their opposition to the Vietnam War. And when Arendt looked out at the world, she did so from Morgenthau’s perspective, seeing a violent global environment not readily susceptible to the demands of moral imperatives. Promises of world peace through international organizations like the League of Nations and the United Nations did not seduce her. Together, they were campaigners for a hard and grim reality against overweening American optimism. To be sure, international relations was not a subject that preoccupied her, but as one scholar has put it, “Her emphasis on the anarchy of the sovereign state system and her skepticism about the regulatory capacity of international law and institutions showed marked affinities with the American realists of her generation.”

Such views only confused many of their academic colleagues, not to mention the rest of their fellow citizens. Here were cold warriors with no illusions about the Soviet Union, who understood the indispensable role of the United States in the reconfigured postwar world and distrusted liberal ideals of internationalism, yet who stoutly opposed McCarthyism, Washington’s fixation on military power and the Manichean anti-Communism of the American establishment. Just because the Soviets embodied evil did not mean the Americans embodied virtue. Were they liberal or conservative? The correct answer is that they were neither, because they approached political questions from a Continental, “un-American” perspective. They were not nationalistic thinkers. “What an idiocy,” Morgenthau once said to Arendt, “to assume that when you write you must of necessity champion a cause.”

Morgenthau once confronted Arendt directly about her politics. At a 1972 conference in Toronto organized around her work, Morgenthau challenged her: “What are you? Are you a conservative? Are you a liberal? Where is your position within the contemporary possibilities?” To which Arendt responded:

I don’t know. I really don’t know and I’ve never known. And I suppose I never had any such position. You know the left think that I am conservative, and the conservatives sometimes think I am left or I am a maverick or God knows what. And I must say I couldn’t care less. I don’t think the real questions of this century will get any kind of illumination by this kind of thing.

Her views couldn’t be confined within the standard categories or with the help of what she called “bannisters”—and neither could Morgenthau’s. “I am nowhere,” she told Mary McCarthy at the same conference. Years earlier, as a young scholar, Morgenthau had similarly declared: “You are asking where I stand politically? My answer is: nowhere.” Left, right, center—these were labels to be attached to people within the American political spectrum, not to outsiders like Arendt or Morgenthau, or to Leo Strauss, or to Henry Kissinger. The many attempts that have been made over the years to pigeonhole them (Was Strauss a neocon? Was Arendt an “icon of the left”? Was Morgenthau a “conservative liberal”?) have only created intellectual confusion.

A tribute to Arendt that Morgenthau wrote in 1977, two years after her death, provides a window on the kinds of discussions these two unclassifiable political intellectuals from “nowhere” must have had over the years (though only Morgenthau’s voice is heard). He expresses admiration for her Origins of Totalitarianism, endorsing her view that totalitarianism was a new form of regime, unknown to the Western tradition of political philosophy that began with Aristotle. It not only gave rise to genocidal ideologies resulting in the deaths of millions but also incorporated thousands of ordinary citizens into operating its efficient killing machines, bureaucratizing mass murder. This was an idea Arendt was to make famous through her endlessly debated phrase “the banality of evil,” from Eichmann in Jerusalem.