One important ingredient in Freud's analysis was the North-Italian village Trafoi where he received the message of the suicide of one of his patients, struggling with sexual problems.
The second important ingredient in Freud's analysis is the extraction of an Italian word signor from the forgotten name Signorelli.
That country's Turks, he recalled, valued sexual pleasure highly, and he was told by a colleague that a patient once said to him: "For you know, sir (Herr) if that ceases, life no longer has any charm".
Trafei, offenbar Anlehnung an Trafoi, ist eine willkürliche Neubildung an Stelle des wirklichen, völlig abweichenden Namen jener Gehölze.
In The Freudian Slip Sebastiano Timpanaro discusses Freud's analysis in chapter 6 "Love and Death at Orvieto."
As to the Signor-element in Freud's analysis he puts: "The immediate equivalence Signore= Herr is one thing, the extraction of signor from Signorelli and of Her(r) from Herzegowina is another."
Peter Swales (2003) investigated the historical data and states that Freud probably visited an exposition of Italian masters in Bergamo mid-September 1898, showing paintings of Signorelli, Botticelli and Boltraffio one next to the other.
The association of the name Boltraffio to the name Da Vinci, another hypothesis formulated by Swales (because Freud might have seen the statue of Boltraffio at the bottom of the Da Vinci monument on Piazza della Scala in Milan some days before his visit to Bergamo), is not further pursued by Swales.
Freud in his analysis did not use the fact that he remembered very well a picture of the painter in the lower left corner of one of the frescos.
[5] Molnar (p.84) remarks that Signorelli and Sigmund share the same syllable, making Freud's parapraxis an act of self-forgetting.
The "signature" can be interpreted as a reference to the Latin verb signare and this word, instead of Freud's signore, then leads to a simple analysis of the Signorelli parapraxis.
In attempting to connect Signorelli to Boltraffio, Freud fails to indicate why he uses some pieces of information while neglecting others.
In a foreword to the second edition Freud expresses his anger that psychiatrists did not cite his Dream Interpretation.