Professor Liberman wrote “Contemporaries of the first ghetto in Venice failed to associate ghetto with borghetto.” The complex sentence has these propositions:
1. why the contemporaries
2. of the first ghetto in Venice
3. failed to associate ghetto with borghetto
4. invented Hebrew etymologies for it.

The Venice Jewish quarter that we now call “il ghetto” was not the first such Jewish precinct, in Venice or anywhere else. The 1516 sequestration of Jews on the Venice island written variously Geto ~ Gheto ~ Ghetto was not the first “ghettoization”. Sequestratiom of Jews and others is common around the world over the centuries. Areas predominantly inhabited by Jews at other times had gentile inhabitants, too. Many foreigners in Venice were segregated (Lucchesi, Lombards, Tuscans, Germans, Muslims). Before 1516 Jews lived on various islands of Venice. The Senate considered segregating Jews on the islands Giudecca (Venetian Zoega) and Murano, but the plans fell through.
It was not in 1516 in Venice, to explain the Venetian island toponym Ghetto, that a Hebrew folk etymology ghet ‘divorce decree’ was invoked by Jewish notaries. It was in Rome, a full century later, and had to do, not with Venice, but with a foul-smelling Roman street (even in the mid 1800s), called Ghetto. In the papal bull Nimis Absurdum (‘enough’s enough’) issued by Paul IV in 1555, the ecclesiastical Latin word used by the pope’s amanuenses was vicus ‘street, vici ‘streets’, not mock-Latin ghectus. In a second papal bull Dudum a felicis (‘it’s about time’), not Venice’s, but the name of Rome’s slum street Ghetto was written ghectus, just as scribes wrote the Italian word tutti ‘all’ as tucti, Matteo as Macthaeo; they wrote quattro ‘4′ as quactro.
In Venice every street is an island, every island a street. A street is a cluster of houses. Italian maps label settlements “case di ‘houses of X”. The people call “the mean streets” a “ghetto”. Northeastern and central Italy have scores of ghetti. The Italian Post Office has postal codes/ZIP Codes for them, CAP (Codice Avviamento Postale).
“Contemporaries of the first ghetto in Venice failed to associate ghetto with borghetto.” —What evidence.is there that they didn’t? Association of the words ghetto and borghetto is inescapable in Italian Sprachgefühl.
Aphesis: for anyone knowing Venetian and Tuscan the connection is unavoidable. Compare in English ’shrooms for mushrooms, drawing room, to which English gentlemen withdrew to smoke, leaving their ladies to their amusements; mend for amend/emend, cute for acute, pert for apert (note the homonymy of the indefinite article (a) and prefixes) Aphesis flourishes in Itralian (and Venetian). In English aAnyone can trace the source of ’puter (my grandson’s creation). Or ’buke (Southern Baptist for rebuke). In the Veneto America is Merica; l’arena is la rena A satirical paper features the head of a reindeer, La Renna, in a logo pun on L’Arena di Verona, adverting to Verona’s famous Roman amphitheater and the major local newspaper.

The source of ghetto is all over the map of Italy, toponomastically and in figurative language.