ON THE MORNING OF May 16, 1933, Max Planck, the president of the Kaiser Wilhelm Society, met with Adolf Hitler in Berlin. It had been more than three months since German president Paul von Hindenburg had made Hitler chancellor, but Planck had been slow to absorb the meaning of Hitler’s ascent.
Planck was not alone in this regard. The German recovery of the late 1920s was spectacular but short-lived. With the collapse of the American stock market in October 1929, bankers in the United States called in the loans that had been propping up German industry. The German economy nosedived again, and no one would benefit more from the return to instability than Adolf Hitler. In the 1930 parliamentary elections, the Nazis received 6.5 million votes, giving the party 107 of the 577 seats in the Reichstag. Two years later, some 6 million Germans were out of work, and the Nazis held 230 Reichstag seats.
Hindenburg had appointed Hitler chancellor on the assumption that he and other German conservatives could contain him. Those who had been paying attention knew better. The very sight of the words “Hitler Reichschancellor” left the German journalist Sebastian Haffner in a state of shock. It “was so bizarre, so incredible, to read it now in black on white,” he wrote. “[F]or a moment I physically sensed the man’s odor of blood and filth, the nauseating approach of a man-eating animal—its foul, sharp claws in my face.”1
By the end of March 1933, the Nazis’ newly built concentration camps were already filling with political prisoners. On April 7, the Reichstag passed the Law for the Restoration of the Professional Civil Service, banning “non-Aryans” (defined as anyone with at least one Jewish grandparent) from government positions, including university posts. Though it would take another five years before virtually all Jews would be purged from public life, German science would never again be the same.
Planck had been on vacation in Sicily when the Civil Service Law went into effect. He chose not to return to Berlin to help manage the crisis even after the Nobel Prize–winning German physicist Max von Laue pleaded with him to do so. Though he had championed individual Jewish scientists in the past, including Emil Warburg and Einstein, Planck, an obedient Prussian, was the wrong man to stand up to a fascist dictator. He would only awaken to the severity of the situation upon learning that Fritz Haber, the director of the Kaiser Wilhelm Institute for Physical Chemistry, had announced he would resign before dismissing the many Jewish researchers in his lab. (Haber was born Jewish but had been baptized, seemingly to advance his academic career.) It was one thing for less prominent scientists to flee Germany; it was another for Haber to leave. Haber had been the architect of Germany’s gas warfare program during World War I. He was a celebrated patriot and a pillar of German science, the institution Planck treasured above all else.
Belatedly, Planck decided to act, and he soon found himself sitting across from Adolf Hitler. According to Planck’s account of the meeting—written with the help of his wife 14 years later and now looked upon with some suspicion by many historians—Hitler told Planck that he had “nothing against the Jews themselves” but that he had to wage war against them because they were all Communists and thus enemies of the Nazis and the German state. Planck suggested that there were “different sorts of Jews, some valuable for mankind and others worthless” and that “distinctions must be made.”
“A Jew is a Jew,” Hitler shot back. “All Jews stick together like leeches.”
Planck claimed to have tried again, mentioning the importance of certain Jewish scientists to Germany. But Hitler had lost interest and turned the conversation to himself. “People say that I suffer from a weakness of nerves,” Hitler said. “That is slander. I have nerves of steel.” As Hitler continued in this vein, he began to speak faster and faster, violently slapping his own knee. “I could only remain silent and withdraw,” wrote Planck. It was a conclusion, arrived at by millions of other Germans at approximately the same time, that would ultimately doom Europe’s Jews.2
While Planck did not mention it, in the days after the meeting, word spread that Hitler had assured Planck that no further restrictions would be imposed on the Kaiser Wilhelm Society. Weeks after his meeting with Hitler, Planck appeared at the society’s annual meeting and read aloud from a telegram the society had sent to Hitler. German science, Planck declared, was ready “to cooperate joyously in the reconstruction of the new national state.”3
For Planck, as for many others, the joy would soon be gone. Three months after his speech, Lotte Warburg ran into an “unkempt” Planck “shuffling through the park” looking “miserable.” When Lotte told him about the latest firings of Jews from German universities, Planck claimed ignorance but didn’t attempt to mask his despair. German science, he said, had become “worthless.”
Lotte Warburg would come to despise Planck for his failure to stand up to the Nazis. “Why does he stand by, without even bothering to offer an explanation, as Kaiser Wilhelm Society members are thrown out?” Lotte wrote in 1934. “Why does he go about stooped over, whining and complaining,” rather than “damning them all?” She was particularly appalled that Planck had omitted Emil Warburg’s name from a public speech about German physics, presumably because he feared even mentioning a Jew.4
With two Jewish grandparents, Otto Warburg was unequivocally “non-Aryan” by the terms of the Civil Service Law. But because the Civil Service Law didn’t apply to privately funded institutes and because Hitler (under pressure from Hindenburg) had made an exception, initially, for veterans of the war, Warburg had less cause for panic than many of his colleagues, at least in the beginning. Hidden away in his institute in Dahlem, he probably didn’t see the stone-faced SS men standing in front of Jewish-owned shops to steer customers away or the menacing mobs of Nazis shouting “Jews out!” in the streets. Warburg might not have heard the reports of brownshirts beating political opponents and sending them off to the newly erected camps. In early 1934, to the amazement of his Warburg cousins, he was not even aware that Germany had withdrawn from the League of Nations the previous October.5
But if Warburg remained ignorant in some respects, he did know that Jewish scientists were being chased out of their jobs. In March 1933, even before the institution of the Civil Service Law, the Prussian Academy of Science began proceedings to oust Einstein for the crime of disparaging the new Nazi government. (Einstein chose to resign before the academy had the chance to dismiss him, a move that further infuriated his Nazi antagonists.) Warburg was appalled by the treatment of Einstein. Every member of the academy should have resigned, Warburg told an official from the Rockefeller Foundation later that year. A strong statement projecting unity, Warburg argued, might have prevented all the actions taken against Jewish scientists that followed.
Though Warburg was not a member of the academy, he did resign from the German Physical Society in solidarity with Einstein. According to his own account, Warburg also stormed out of a meeting of the directors of the Kaiser Wilhelm Society institutes, disgusted by the Nazi sympathizers in the room who were prepared to give Hitler control of the society.6
Warburg’s displays of indignation, of course, made little difference. In the first year after the Civil Service Law came into effect, an estimated 2,600 scientists and other scholars—almost all of them Jewish—fled Germany. Hans Krebs, who was Jewish, had just started in a new faculty position in Freiburg when the new regulations were announced. He continued to go to work for the next few days, unable to fathom that he would really be dismissed. Warburg wrote to Krebs, offering to let him return to his institute, while adding that a move to England did seem the safe choice, given that “we have no idea what is still to come” in Germany.7
Krebs chose England. Unable even to return to his lab to pack his belongings, he had them shipped. In the cargo were the Warburg manometers that he would soon use to decipher a series of reactions—now known as the Krebs cycle—that revolutionized our understanding of metabolism.
IF FAR FROM A public champion for the persecuted, Warburg may have been more reckless and confrontational than any other German scientist of the era. The most astonishing aspect of Warburg’s story isn’t that a gay man from a famous Jewish family survived in Germany; it’s that he managed to do so even as he provoked the Nazis at every opportunity.
It wasn’t that Warburg was oblivious to the danger he faced. By the end of 1933, he would have already sensed that no one with Jewish ancestors could feel entirely safe in Germany. Emboldened by the rise of the Nazis, anti-Semites from every sphere of German society were emerging from the shadows to flaunt their hatred. In June 1933, a Berlin engineer published a pamphlet calling the Kaiser Wilhelm Society a “breeding ground for Jewish exploiters, oppressors, and Marxists.” German science had become “the servant and slave of these vampires,” who profited from their ideas and shared their riches with Jewish conspirators. The pamphlet specifically attacked the Jewish leaders of the various institutes. “The Jew Professor Warburg,” it stated, “enriched himself with the inventions of his associates while they were starving with their children.”8
Warburg’s first show of resistance was to ban his employees from making the Nazi salute or hanging the Nazi flag at his institute. Through 12 years of Nazi rule, he would defy Nazi orders again and again, just as he did in 1934, when he chased the customs official demanding a “declaration of Aryan descent” out of his institute. On one occasion, a young woman at another institute asked Warburg if she was still allowed to use animals in her experiments, citing reports she had read in the newspapers that it had been forbidden by the Nazis. “You should stop reading the newspaper,” Warburg told her.
In another instance, a group of Nazi officials arrived at Warburg’s institute to check on whether everyone present had registered with one of the many new Nazi bureaucratic offices. Warburg, according to Lotte’s telling, politely dismissed them, telling them that his employees were working hard and had “no time to deal with politics.”9
On still another occasion, a company of storm troopers arrived at Warburg’s institute and said that five of Warburg’s assistants needed to leave for the day to take part in a mandatory Nazi march. Warburg asked the leader of the group to identify himself and then told the man that he “would burn his institute” before allowing it to be interfered with in such a way. The storm troopers left and never came back.10
Warburg’s finest moment during the Nazi years may have been his protection of Erwin Haas, a Jewish researcher who remained at his institute until 1938. When a Nazi official phoned to instruct Warburg to fire Haas, Warburg said it was impossible and that he would resign before doing so. In February of 1935, Warburg mentioned Haas’s situation to a Rockefeller official and reiterated that he would quit if he faced any political interference.11
David Nachmansohn thought it was ultimately Warburg’s aristocratic nature that led him to hate the Third Reich: “It is easy to guess how much he must have despised the Nazi mobs, the vulgarity of their mass meetings, the low stature of the men with whom Hitler surrounded himself.” As Warburg put it, he was not going to let “a handful of arbitrary criminals” and Bavarian “noisemakers,” as he called the Nazis, tell him what to do.12
Warburg’s record in the first half of the 1930s was far from perfect. He did let go of one young Jewish researcher, Walter Kempner. In a letter to Kempner’s mother, Warburg claimed Kempner had not been working the required hours. Warburg had already fired Kempner once before, in 1929, for making an arrogant remark, of all things. Kempner had only been working at Warburg’s institute for a brief period when Warburg fired him again, and Kempner was known to be an eccentric—many years later he would become a diet guru in the United States who sometimes physically abused patients.13
Warburg did try to find a position for Kempner in America. And given that the two maintained a warm correspondence for the next three decades, Kempner presumably didn’t blame Warburg for his dismissal. But that Warburg was ready to make a stand for Haas and apparently unwilling to do the same for Kempner was likely a reflection of Warburg’s broader outlook in the early 1930s. He could tolerate an injustice to a Jewish scientist so long as it didn’t impact him in a meaningful way. Kempner had only been back at the institute a short time and wouldn’t have been missed. Haas was a great scientist, an important member of Warburg’s team.14
Had he left Germany like so many others, Warburg could have avoided these moral quandaries. On a number of occasions, he declared that he was on the verge of leaving. In May 1933, Warburg told a Rockefeller official that he saw “no future” in Germany and that he planned to leave as soon as he found a new position elsewhere. According to a Rockefeller memo, Warburg already had an offer from the University of Leeds. That summer Warburg broached the subject of leaving Germany with Max Warburg. “The only country I might consider is England,” Warburg told Max, “but can you imagine my having to talk to other professors?”15
Worse than mingling with academics would have been departing Germany as a refugee. Warburg once told a Rockefeller official how disturbed he was to have seen his name mistakenly added to a list of displaced German scientists. In retrospect, fleeing Germany appears to have been a moral imperative, but in the early 1930s, German Jewish scientists typically saw it as a source of great shame, an acknowledgment of one’s inferiority. And Warburg, by his nature, would have been highly sensitive to this humiliation. His sense of his own greatness coexisted with profound insecurities. He lashed out whenever his work was criticized precisely because the criticism stung so deeply. Near the end of his life, Warburg remained full of antagonism for Richard Willstätter, a famous organic chemist. Willstätter’s great offense? He had once been dismissive of a question Warburg had asked at one of his lectures. “Five hundred people laughed,” Warburg recalled decades later.16
Besides, Warburg saw no good reason to flee. He had served as an officer in World War I—as an uhlan, no less. He was a German through and through. When Lotte expressed doubts about her own future in Germany, Warburg reminded her in a letter that whatever her financial concerns might be, the question of “what happens to your sense of self when you live somewhere you weren’t born” would remain.17
Warburg, for all his personal faults, knew who he was and how exile would affect him. The famed Austrian writer Stefan Zweig had wrestled with the same dilemma: to live under the Nazi jackboot and hold on to whatever might be left of his prestige and status, or to flee and start anew. Zweig took the latter path and never recovered. “Everything which I had attempted, achieved, learned, enjoyed,” Zweig wrote, “seemed wafted away.” Not long before committing suicide in 1942, Zweig described his life in exile as a “posthumous” existence.18
For a German patriot like Warburg, fleeing Hitler wouldn’t only lead to shame and a loss of identity. It would be an implicit acknowledgment of having been mistaken about Germany itself. As Einstein wrote to Fritz Haber in 1933, recognizing Germany for what it had become was “somewhat like having to abandon a theory on which you have worked for your whole life.” And if there was one thing Warburg did not do, it was admit to a mistake or abandon a theory.19
The reason for leaving Germany—that he was a Jew—made the entire notion all the more absurd to Warburg. Like many Germans of Jewish descent, he had never identified as a Jew and felt no special connection to the larger Jewish community. As Zweig observed, the persecuted Jews of medieval times “had at least known what they suffered for.” And who was Hitler, of all people, to send Warburg away? Warburg told Lotte that he had looked closely at a photo of Hitler and concluded that he wasn’t even a true German. Warburg suspected Slavic descent.20
Warburg also had more concrete reasons for staying. Leaving Germany would have meant giving up his stunning new institute. Though it was part of the Kaiser Wilhelm Society, it was funded by a private US foundation, and Warburg had secured the funding himself. A young researcher claimed to have heard a Rockefeller official offer to take pictures of the institute so that a perfect replica could be built for Warburg elsewhere, but there is no evidence that the Rockefeller Foundation considered building an entirely new institute for Warburg. “[T]here are, to my knowledge, very few departments in the world that are more amply equipped and endowed than those of Meyerhof and Warburg,” one foundation official noted. “I doubt if one could find anyone who would be in a position to create an institute for either one of them. The best hope would be for the occurrence of a vacancy” at an existing institution.21
The worst part of relocating, Warburg told Krebs, would be losing technicians he had spent years training to carry out his experiments. (Warburg claimed he could communicate with his employees just by glancing at them.) Though speaking about Meyerhof, Warburg was also clearly referring to his own dilemma when he argued that it was especially hard for a distinguished researcher to leave. It “is easy to find a place for an ordinary person,” Warburg said, “but it is hard for a king to find a kingdom.”22
Among the better explanations for why Warburg stayed in Germany after Hitler became chancellor is the simplest of all: during the first year of Nazi rule, he failed to grasp how bad the situation would become. Warburg was convinced that the Nazi experiment would implode as Hitler crossed lines that a civilized country could not cross. Warburg’s opinion was common in the early 1930s. Millions of other Germans, including many German Jews, suffered from the same myopia. Hitler, Eric Warburg said in 1933, should be given “enough rope to hang himself.”23
On the morning of June 16, 1934, Warburg met the Rockefeller official W. E. Tisdale for tea and said that “less ignorant” and “more moderate forces” were “gaining ground.” The two continued the conversation over lunch at Berlin’s Hotel Continental. After the meal, they spoke outside so as not to be overheard. The German army would come to the country’s rescue and restore the monarchy, Warburg said, as the two men paced back and forth in front of the hotel. He gave the Nazis only another six months.24
Warburg, anxious about losing his Rockefeller funding, was probably going out of his way to make Germany’s future appear less bleak. If he did believe what he told Tisdale, his opinion soon changed. The following May, Warburg told Lotte that the Nazis were “the greatest criminals in history” and that the political situation had “swallowed science whole.” He said he’d begun telling “the non-Aryans” he encountered that it was “almost their duty” to do everything possible “to bring these people to their knees and undermine the state.” “If you have even the slightest thing to do with these criminals,” Warburg continued, “you are despicable.”
Warburg also told Lotte that he wanted nothing to do with Germany as long as the concentration camps (still, at the time, used mainly for political prisoners) and secret police remained in existence. But for Warburg, wanting nothing to do with Germany didn’t necessarily mean wanting to flee Germany. If anything, it meant the opposite. He was “boiling with rage against Germany,” Lotte wrote in her diary. And the “more he hates, the more firm is his decision to stay put.” Warburg had closed himself off in his home and institute “like a foreign prince” among the German people. “He tells himself it is nothing more than a test of strength and nerves to see who can outlast the other: them or him.” Added Lotte, “And I hope it’s him.”25
Lotte, too, was struggling with the question of whether to stay or flee, and Warburg’s advice to his sister is revealing: “He advises us first to stay and then to leave,” Lotte noted. “He always contradicts himself.”
Later that year, Warburg again mentioned the possibility of leaving for England if he could find a position suitable to his reputation. But he refused to leave, he said, if it would appear that he was being kicked out. Before being humiliated by Nazi lowlifes, Warburg promised to wait until “everything collapses.”
Lotte recorded Warburg’s words in her diary and then appended a comment of her own: “I fear if he only leaves when everything here collapses, it will be too late.”26
FOR WARBURG AND others deemed “non-Aryans” by the Nazis, a turning point came late in 1935 with the introduction of the Nuremberg Laws. Through campaigns of violence and economic sanctions, the Nazis had already made life unbearable for most of Germany’s remaining Jews. But Nazi hardliners, frustrated by what they saw as a slow pace of change, believed that the existing measures weren’t severe enough. Some had begun to take matters into their own hands, forming lynch mobs to attack Jews suspected of having sex with Aryans. The Nuremberg Laws were designed to satisfy this hunger for additional cruelty. The cruelty, in a sense, had always been an end in itself. In the words of one historian, it was “I kick, therefore I am.”27
One of the two Nuremberg Laws, the Reich Citizenship Law, stripped Jews of their German citizenship and made them subjects of the state. The Law for the Protection of German Blood and German Honor made it a crime for Jews to marry or engage in extramarital relations with the “German-blooded.” But these new laws, which the Nazis said would bring clarity to their Jewish policies, had the opposite effect.
In the original draft of the law banning relations between Jews and the “German-blooded,” the text had included a significant line: “This law only applies to full Jews,” defined as someone with three or four Jewish grandparents. Believing it would limit the international outcry, Hitler left this reference to “full Jews” in place in the draft that was sent to the government press agency. But in the draft sent to the Reichstag, Hitler crossed the line out in pencil. With that single pencil mark, he changed the fate of the hundreds of thousands of Germans who had only one or two Jewish grandparents.
The two different drafts of the law left German officials unsure whom it applied to. Most Nazi Party officials wanted to continue to define Jews, or non-Aryans, by the terms of the 1933 Civil Service Law, which applied to anyone who had even one Jewish grandparent. But those serving in government posts, conscious of Germany’s international reputation, called for a more nuanced stance. The Berlin Olympics were less than a year away, and, though it was assumed that the international community would tolerate cruelty against Jews, it was less clear if it would tolerate attacks against the so-called half-Jews and quarter-Jews, who typically thought of themselves as Christians.
The Nazis referred to Germans with only one or two Jewish grandparents as Mischlinge, a derogatory term that translates to something like “mongrel.” Hitler detested the Mischlinge, calling them “monstrosities halfway between man and ape.” He once said that half-Jewish blood would not “Mendel out” even after six generations of descendants reproduced with so-called pure Germans. The Mischlinge were the living embodiment of Hitler’s nightmare, in which tainted Jewish blood mixed with pure Aryan blood with impunity. In the Mischlinge, Hitler wrote in Mein Kampf, “the vices of the parents are revealed in the sicknesses of the children.”28
Nevertheless, as the debate over the new law intensified, Hitler wavered. That the Mischlinge would eventually meet whatever fate awaited “full Jews” was a given. But Hitler recognized that the persecution of the Mischlinge was more than a threat to Germany’s international reputation. Mischlinge had millions of “German-blooded” relatives who might turn against the Nazis if members of their own families were humiliated and persecuted. Many Mischlinge were still serving in the German army at the time, including at the highest ranks.
In the end, Hitler sided with the “moderates.” In November, two days after Lotte Warburg wrote in her diary that her brother was waiting for the moment when “everything collapses,” a supplementary decree was added to the Nuremberg Laws to distinguish full and partial Jews. Those with two Jewish grandparents, like Warburg, were deemed “first-degree Mischlinge,” while those with only one Jewish grandparent were labeled “second-degree Mischlinge.” Though not subject to all of the same decrees as “full Jews,” Mischlinge would still be denied positions of authority and robbed of most of the rights of German citizens. For the time being, they could still be drafted into the army, but would now be restricted to the lowest ranks. While Mischlinge were not legally barred from studying in universities, various areas of study were off-limits. In some cases, Mischlinge were barred even from their own churches.29
THE FIRST STEP in both respiration and fermentation is a splitting known as glycolysis: one glucose molecule is broken into two. The biochemical reaction that had captured Otto Warburg’s scientific imagination was now a metaphor for his life. He had always been divided in two, in various ways. He was both a nineteenth-century aristocrat and a modern scientific visionary, a charming conversationalist and a self-important dictator. Upon being legally declared a first-degree Mischling, or half-Jewish and half-Aryan, he had been split down yet another fault line.
Though there are no records of Warburg speaking directly about his new legal status, many other Mischlinge did. They were typically devastated and humiliated to have been classified as second-class citizens. By the terms of the Nuremberg Laws, Warburg could have been arrested for having an intimate relationship with an Aryan—a crime known as “race defilement.” Warburg, a half-Jew, could have been arrested even for having relations with a quarter-Jew.
As neither “true” Jews nor “true” Germans, the Mischlinge were caught in the middle of the Nazis’ disturbed race fantasies. Bernhard Lösener, an official at the Reich Ministry of the Interior, once said that the Mischlinge had it worse than the “full” Jews, who at least had a community to belong to. The Mischlinge were stranded between two worlds: half-Jew, half-Aryan; half-oppressed, half-oppressor.
Even before the introduction of the Nuremberg Laws, the Nazis had made it difficult for Warburg to work without evidence of Aryan heritage. His situation now became all the more desperate. Warburg continued to invite young scholars to his institute, but fewer and fewer would accept the offer. Some thought Warburg’s friendly invitations to study at his institute had to be a joke. One English scientist laughed in Warburg’s face when he proposed a visit to Berlin. His status as a “half-Jew,” Warburg said, made his institute an object of such “disdain” that even being associated with it came with the risk of ruining one’s academic career.30
On January 13, 1936, the New York Times ran a critical editorial on the declining state of the Kaiser Wilhelm Society: “The fate of even such eminences as the physiologists Otto Warburg (supported by the Rockefeller Foundation) and Otto Meyerhof is avowedly precarious.” Carl Neuberg, who pioneered the modern study of fermentation and who was among the most prestigious chemists in the world, had remained in Germany even after being dismissed from his position as head of the Kaiser Wilhelm Institute for Biochemistry in 1934. In 1936, in a desperate effort to hang on to his career and life in Dahlem, Neuberg suggested that his equipment be moved to a gatehouse on the grounds of his old institute. Even this feeble request was denied.31
For all his defiance when the Nazis attempted to directly interfere with his institute, Warburg told his Jewish colleagues at other institutions to lie low and hope that the Nazis would forget about them. Public statements against the government, Warburg warned, would only make things worse for German Jews. His advice to Meyerhof was to “sit tight and do nothing.” But with each passing year, Warburg’s claims that the Nazi nightmare would soon be over became less plausible. In the middle of the decade, Hitler was growing more rather than less popular.
Warburg’s own fame and popularity spread even as he had become a pariah in Berlin. In 1936, the American radio program Heroes of Civilization produced an episode about one of Warburg’s minor findings, complete with an actor playing Warburg. That same year, Warburg planned to attend a conference of international scholars in Cambridge, Massachusetts, in honor of Harvard’s 300th anniversary. Warburg was delighted by the invitation. “Everything that I have become, everything that I have, I have received from foreigners,” he told Lotte. “That’s why I completely feel like a foreigner in this country and live as one here, too.”32
The appearance at Harvard would never take place—Warburg canceled shortly before it started. A ship manifest for the SS Europa, which sailed for the United States in August 1936, shows Warburg’s name crossed out. The physicist Werner Heisenberg also failed to attend despite planning to. A Boston Globe report on the Harvard conference noted that the two scientists missing from the event seemed to be inspiring “more talk” than “all who have appeared.”33
While the precise circumstances of the cancellation are unknown—Harvard was told only that Warburg had to attend to “unexpected duties”—Warburg was almost certainly forbidden from attending by German authorities. In the buildup to the Berlin Olympics of 1936, the Nazis were busily spreading propaganda to distract from their anti-Semitic policies. Warburg had become politically useful, evidence that a Jew could still live and work in Germany.
Warburg was aware that he served this function for the Nazis. He told Lotte that he suspected there was a note next to his name in a Nazi register somewhere that read, “retain for another ten years for foreign propaganda.” By remaining in Germany for so long, he told Lotte, he had made a “devil’s pact” with the Nazis.34
As Lotte once put it, Warburg’s decision to remain in Nazi Germany was made possible only through theater. Her brother, Lotte wrote, had “decided to play the role of the man with no soul.”35
In becoming a tool of the German authorities, Warburg, perhaps without knowing it, was carrying on a centuries-old family tradition. He was a direct descendant of Simon von Cassel, the sixteenth-century Warburg family patriarch who was allowed entry into the German town of Warburg to work as money changer and pawnbroker. Church prohibitions against money lending led Jews into such roles, even as they were barred from many other professions. Simon and his descendants were Schutzjuden, or “protected Jews.” Though still treated as second-class citizens, they were granted special privileges by the local rulers and functioned as leaders of the Jewish community, with Simon’s home doubling as Warburg’s synagogue. The Warburg family “hung from a golden thread, suspended between gentiles above and Jews below,” the historian and biographer Ron Chernow wrote in his book on the Warburg family. “This ambiguous, hybrid status—neither totally Jewish nor gentile—contributed to the deeply schizoid Warburg character.”36
As late as January 1937, Warburg was still capable of feigning optimism. A Rockefeller official who dined with Warburg that month described him as “less disturbed and uncertain than in the summer of 1934.” During the meal, a defiant Warburg described the Nazis as “labile” and mocked their militarism: “Force is not strength, nor is pomp dignity,” he said, quoting an English acquaintance.
Later that year, Warburg received permission to travel to Paris for a scientific conference. When he arrived with Heiss, he checked in at the German embassy. Lotte, who was also in Paris at the time, noted that Warburg “dressed very solemnly” for his visit to the embassy, wearing all of his war medals. But when he arrived at the embassy, he found it empty and grew angry.
Lotte had left Germany permanently by that point and was living in The Hague. Warburg filled her in on his life in Dahlem. One day, he said, he was in Max Planck’s office together with Friedrich Glum, the general secretary of the Kaiser Wilhelm Society. Standing at the door, Warburg turned to the two other dignitaries of German science and offered a parting remark: “Hitler,” Warburg announced, was said to have been “surprised at the cowardice” of the gentile professors who had failed to stand up to him.
Warburg also told Lotte that he now ignored Planck whenever the latter tried to speak with him and that Planck had stopped trying as a result. Lotte herself remained enraged at Planck. “Until the end of his life, he will wear the mask of the noble, selfless, persuasive and true researcher,” she wrote in her diary. “And no one will ever discover the monumental cowardice and lack of character that filled his last years.”
Planck, however, was the least of Warburg’s concerns in 1937. Living anything resembling a normal life in Germany now required concrete proof that one had no Jewish heritage, and various Nazi officials were regularly calling Warburg in for questioning. In response to such queries, Warburg simply lied, telling the police and the officials hounding him that he was a pure Aryan. He had no choice, he explained to Lotte. Life would be “unbearable” if he didn’t pretend.37 Warburg claimed that some of the Nazis believed him and that the ones who knew he was lying didn’t dare confront him. It’s more likely that they all knew he was lying. “With a name like Warburg” his denials were “a feat that required remarkable nerves,” Lotte noted.38
It’s unlikely that Warburg would have fared much better with a less obviously Jewish name. The Nazis had turned centuries of baptism records from Protestant churches into an immense genealogy registry. The files gathered from dingy church basements sometimes left room for ambiguity, but there were other options in such situations. Warburg’s colleagues at the Kaiser Wilhelm Institute for Anthropology could be called on to determine someone’s racial purity according to the shape of the individual’s head or nose.39
Three years earlier, Warburg had vowed that the Nazis wouldn’t scare him away. Now he was paralyzed by indecision. He had debated leaving “a hundred times,” he told his sister, but he still could not make up his mind.40
THE YEAR 1938 began on a particularly unsettling note for Otto Warburg. He could have been arrested by the Nazis for almost any reason, but on January 12 he was confronted with even more alarming news: he was dead. That, at least, is what was reported in The Times of London, which ran an obituary for Warburg on that day.41
Warburg sent off an angry message to The Times, and the paper apologized for the mistake the next day: “We much regret that by an unfortunate misunderstanding we announced yesterday the death of Professor Otto Warburg, the biologist, who is, we are glad to learn, still living.”42
The man who had died was a different Otto Warburg, a cousin who, in addition to being a distinguished botanist, was a former head of the World Zionist Organization. Warburg was able to find dark humor in the obituary. He pinned the article near his workspace and brought it up throughout the day, saying over and over that he could have written a much better version himself. “It looks as if the obituary was written jointly by poor old Heinrich Wieland and poor old Torsten Thunberg,” Warburg joked, a reference to two of his scientific adversaries. But he was said to be genuinely upset that the obituary had failed to mention a number of his most important discoveries. For a man convinced of his own greatness and intent on leaving a lasting mark on humanity, the mere three-paragraph obituary must have come as a terrible blow.
The problems ran deeper still. Referring to his cousin of the same name, Warburg claimed, in an uncharacteristically personal letter to a Rockefeller official, that “the elderly gentleman, whom I do not know and who must be around 100 years old, has caused a lot of confusion in my life. . . . His very existence is practically an impediment to my individuality.” Indeed, even the Nazi bureaucrats monitoring Warburg once mixed him up with the other Otto Warburg.43
That there were two Otto Warburgs, one an ardent Zionist and one detached from his Jewish background and working in Nazi Germany, was almost too perfect. It was the “schizoid Warburg character” come to life in the form of two distinct individuals. The other Otto Warburg was not only an impediment to Warburg’s individuality but an indictment of his entire person. If the Warburgs were “suspended between gentiles above and Jews below,” Warburg’s Zionist namesake had reached down. Warburg himself would only reach up.44
Whether the obituary was still on his mind several weeks later, on the day Warren Weaver from the Rockefeller Foundation arrived at his institute, is impossible to know. Warburg was sitting in his library, talking to a young researcher, when Weaver appeared at the door. After the researcher left the room, Warburg “with a somewhat cynical smile” told Weaver he had just received a call from Richard Kuhn, the director of the Kaiser Wilhelm Institute for Medical Research, who would be chosen for the Nobel Prize later that year. Warburg said that he had picked up the phone, told Kuhn “I will not speak with you,” and then hung up. “I treat them like dogs,” Warburg announced, “for that is indeed what they are.”
Warburg had good cause to despise Kuhn, who had earlier denounced Meyerhof for his attempts to protect his Jewish employees. Even so, what Warburg said next, that Kuhn and several other Kaiser Wilhelm directors were “rotten to the bone” and scheming only for their own power, shocked Weaver. “One got the impression of a man who, however keen his mind may be when directed toward his scientific research, is nevertheless very near the edge of mental instability,” Weaver wrote. That Warburg “is suffering from an intense and perhaps even unsuspected kind of loneliness is clear; that he has a fairly well-developed persecution complex seems almost as clear.”45
Weaver’s assessment wasn’t particularly sympathetic, given that Warburg had already faced years of persecution. And Warburg’s situation was only becoming more dire. Though he had been allowed to travel with permission in 1937, in August 1938 the Nazis stopped him from attending the International Congress of Physiology in Zurich, where he had planned to present a paper. Warburg sent a telegram to the organizers: “Must cancel attendance,” he wrote. “There is no reason.”46
“No reason” would have been understood as a coy comment on the irrationality of the Nazis. The conference attendees were thrilled by Warburg’s subversive message. And Warburg continued to defy the Nazis throughout 1938. He trashed an invitation to a reception in honor of Planck’s 80th birthday the moment it arrived. When Warburg’s last Jewish employee had left his institute that year, the Gestapo asked Warburg how he had dared to keep a Jewish employee for so long. Warburg responded that the man was a Hungarian Jew and that he had thought the rules only applied to German Jews.47
If still capable of lashing out, Warburg no longer did so with the bravado of previous years. Norman Davidson, a young Scottish researcher who had made the surprising decision to study at Warburg’s institute during this period, recalled that Warburg “made no secret of the fact that he detested the Nazis.” But while Warburg allowed Davidson to keep working on an official Nazi holiday in the spring of 1938, he told him to stay away from the windows. Warburg even switched off the fuses so that Davidson wouldn’t accidentally turn on a light.
Warburg’s institute, Davidson wrote, was the only one left in Dahlem that had no Nazis on its staff. At the other Kaiser Wilhelm institutes, some staff members regularly appeared in their black SS uniforms and were more interested in discussing politics than science. Davidson remembered once visiting Adolf Butenandt, the director of the Kaiser Wilhelm Institute for Biochemistry. The institute, he recalled, was full of “rabid Nazis.” “He received me kindly,” Davidson wrote of Butenandt, “but when he asked where I was working in Berlin, and I told him in Warburg’s Institute, his attitude to me became very cold indeed.” Davidson was “quickly shown the door.”48
In September 1938, Otto Meyerhof escaped Germany for France. (When the Nazis invaded France, he would make a dangerous journey across the Pyrenees to avoid capture.) Meyerhof had departed just in time. Two months later came Kristallnacht. Amid the burning and plundering of synagogues and Jewish businesses, 91 Jews were killed and another 30,000 arrested. Many of the Jews still living in Dahlem were brought to the local police precinct. When no instructions arrived from Berlin on what to do with them, the precinct commander let them go.
There is no evidence that Warburg was harassed during Kristallnacht, but only two days later, a traveling exhibit known as “The Eternal Jew” opened in Berlin. The exhibit, which documented the supposed worldwide Jewish conspiracy against Germany, featured caricatures of Jews with grotesquely large noses. It also featured a photograph of Warburg.
The Kaiser Wilhelm Society managed to have Warburg’s photo removed from the exhibit the next month after Warburg provided a Nazi official with information about his ancestry and insisted, as he had before, that he was not related to the famous Warburg bankers.49
Warburg could feel the world closing in on him now. In February 1939, in a letter to a colleague in England, he denied that he had ever sent the “there is no reason” telegram to the physiology conference and asked for help in squelching the gossip. If he didn’t stop such stories from spreading, Warburg added, his actual obituary would soon appear in The Times.50
The following month, in response to additional Nazi inquiries, Warburg once again stated that he was not a Jew according to the Nuremberg Laws. At approximately the same time, Warburg met with a physiologist who had been offered the position of chair of physiology at Berlin University. After first checking to make sure no one could hear him, he instructed his colleague to stay away.
“Germany,” Warburg said, “is heading for a great catastrophe.”51
“THE ETERNAL JEW,” the German variation on “the Wandering Jew,” is a mythical figure from medieval folklore, who, like Faust, captivated the German imagination for centuries. According to the legend, Jesus was carrying his cross to Calvary when he paused to rest on a doorstep of a home. The homeowner, a Jewish man, scolds Jesus for loitering on his property and is punished with the curse of eternal wandering. “I go,” Jesus says, “but you will walk until I come again.”
The Nazis saw the Eternal Jew as a metaphor for the Jew’s never-ending malice—a character who, in his refusal to vanish, justified the famous German slogan, “The Jew is our misfortune.” But German Romantics of the eighteenth and nineteenth centuries had, at times, humanized the Eternal Jew and marveled at his suffering. In one popular late eighteenth-century poem, Christian Friedrich Daniel Schubart depicts the Eternal Jew standing alone atop a mountain, casting down the skulls of the relatives he has outlived and crying out over his inexplicable survival. “I cohabited with poisonous snakes, and pinched the dark-red crest of the dragon,” the Eternal Jew wails, “the serpent stung, but could not kill me; the dragon tormented, but could not destroy me.”52
Otto Warburg, 1931.