In his discussion of the case of Little Hans, Freud adds a footnote in relation to Little Hans’ discovery that women really do not possess a penis. He writes,

I cannot interrupt the discussion so far as to demonstrate the typical character of the unconscious train of thought which I think there is here reason for attributing to little Hans. The castration complex is the deepest unconscious root of anti-Semitism; for even in the nursery little boys hear that a Jew has something cut off his penis-a piece of his penis, they think-and this gives them a right to despise Jews. And there is no stronger unconscious root for the sense of superiority over women. Weininger (the young philosopher who, highly gifted but sexually deranged, committed suicide after producing his remarkable book, Geschlecht und Charakter, Sex and Character [1903]), in a chapter that attracted much attention, treated Jews and women with equal hostility and overwhelmed them with the same insults. Being a neurotic, Weininger was completely under the sway of his infantile complexes; and from that standpoint what is common to Jews and women is their relation to the castration complex.