Quoting Tony Greenstein’s Zionism During the Holocaust: The Weaponisation of Memory in the Service of State and Nation, pages 58–60:

When a friend of Ruppin called him an anti‐Semite he retorted ‘I have already established here [in his diary] that I despise the cancers of Judaism more than does the worst anti‐Semite.’⁸⁸ Ruppin associated Judaism with capitalism and his writings reflected his belief in the identity between anti‐Semitism and anti‐capitalism. His diary contained entries that were symptomatic of self‐hatred.⁸⁹

The issue of the physical image of the Jew troubled Ruppin.⁹⁰ At a theatre performance he complained about the ‘Jewish physiognomy of one of the actresses.’ He subscribed to the myth, much loved by the [Fascists], that the Jews had an especially strong sex drive, hence circumcision.⁹¹

On 16 August 1933 Ruppin described how, five days previously, he had travelled to Jena:

to meet Prof. Hans F.K. Günther, the founder of [Fascist] race theory. The conversation lasted two hours. Günther was most congenial… and agreed with me that the Jews are not inferior but different, and that the Jewish Question has to be solved justly.⁹²

Hans Günther, a member of the [NSDAP] from 1929, was Heinrich Himmler’s ideological mentor and ‘the highest scientific authority concerning racial theory.’⁹³ In May 1930 he was appointed Professor to the Chair in Racial Anthropology at Jena University, after the intervention of Wilhelm Frick, the [German Reich’s] first [Fascist] state minister. Günther praised Zionism ‘for recognizing the genuine racial consciousness (Volkstum) of the Jews.’⁹⁴

This meeting appeared in the German edition of Ruppin’s diaries but was omitted from both the English and Hebrew editions, which were edited by Alex Bein. Bloom wrote of how:

the idea of segregation was central to Ruppin’s eugenic planning… in order to produce a culture of their own, the Jews had to live… separated from any other culture… only such ‘kinship of race’ would encourage him to be healthy and creative.⁹⁵

Lewis Namier, a former Political Secretary of the ZO in London and the personal secretary of Weizmann during the 1930s wrote the preface to Ruppin’s Jews in the Modern World, which appeared in 1934, a few months after the Ruppin‐Günther meeting. Bloom described how:

Weizmann — who worked closely with Ruppin — read it and had to warn Namier not to be so open in expressing their common toleration of [Fascism] (my emphasis)

Because:

the louts will say, the Jews themselves think that it will be all for the good, etc.⁹⁶

Namier was seen, even by many Zionists, as ‘an intense Jewish anti‐Semite.’ He wrote that:

not everyone who feels uncomfortable with regard to us must be called an anti‐Semite, nor is there anything necessarily and inherently wicked in anti‐Semitism.⁹⁷

In his final book, The Jew’s War of Survival, Ruppin wrote that the [Fascist] race laws were:

returning to Judaism those Jews who had been lost to it because of increased assimilation in Germany.⁹⁸

Bloom commented that ‘Ruppin’s attitude towards the [Fascists], then, reflects the general reaction of many Zionists, including “liberals” like Weizmann.’⁹⁹ It [may be] true that the leading Zionists had no reason to foresee the Holocaust but nonetheless their reaction to the rise of Hitler was shameful.

Amos Morris‐Reich asked why Ruppin didn’t express any reservations about Günther in the privacy of his diary, instead describing it as a ‘pleasant encounter.’¹⁰⁰ Ruppin’s Sociology of the Jews ‘incorporated many of Günther’s ideas and theories in the text.’ One of its main sources of inspiration was Houston Stewart Chamberlain, Hitler’s ‘John the Baptist’.¹⁰¹

Ruppin saw Günther’s writings as ‘a treasure chest of material’. Bloom argued that Ruppin’s ‘nationalist‐Zionist view and his view of race are closely connected’.¹⁰² Morris‐Reich, however, argued that Ruppin’s concern with ‘racial unity’ of the Jews was ‘not to be confused with racial purity’. He argued that Ruppin’s opposition to Jewish assimilation was based on his view of ‘racial uniqueness’ as a ‘component of national uniqueness.’¹⁰³ But that is precisely what makes Zionism racist!

Morris‐Reich accepted that there wasn’t simply an identity of interest between Zionism and [Fascism] but also an ideological affinity. He argued that Ruppin’s concern was ‘eugenic rather than racial.’ A distinction without a difference. What is the purpose of eugenics if not ‘improving’ the ‘race’?

Ruppin saw a problem:

where Jews live in the midst of peoples whose racial make‐up is very different from theirs. This seems to be Ruppin’s and Günther’s common ground: that a solution to the Jewish problem must include the Jews’ removal from Northern Europe.¹⁰⁴

Morris‐Reich found these statements, in the light of the Holocaust, as ‘insensitive’ and ‘unfortunate in the extreme’. Nonetheless he argued that ‘Ruppin’s project was nationalist, whereas Günther’s was international.’¹⁰⁵ These are verbal semantics. Clearly Ruppin and Günther shared a lot in common.

Morris‐Reich’s main objection to Bloom’s critique was that he was using Ruppin as an example of the ‘essence’ of Zionism whereas Ruppin ‘never developed a social‐Darwinist theory’. But Ruppin went further than espousing a theory. He put Social Darwinism into practice, for example with his treatment of the Yemenite workers.¹⁰⁶

Bloom argued that Ruppin’s interaction with the [Fascists] cannot be dismissed as simply realpolitik. Rather it was ‘clearly the outcome of a congruent weltanschaung’. For Ruppin and many other eugenicists, ‘the pre‐mass murderer Hitler seemed a refreshing politician.’¹⁰⁷

The encounter between Günther and Ruppin … must be seen as part of Ruppin’s series of ‘friendly’ meetings with the Nazi Foreign Office and Treasury Office.¹⁰⁸

Bloom suggested that Ruppin’s meeting with Günther had practical implications for the plan he was promoting for the emigration of German Jews. They were also preliminary to discussions about the Haʻavara Agreement. Ruppin ‘wanted to reassure the [Fascists] as to the Zionist movement’s deep understanding of the therapeutic and eugenic dimension of such an agreement.’¹⁰⁹

(Emphasis added in most cases.)