Gelli's wrote an important historical treatise, the ''Trattatello sull'origine di Firenze''. The work is based on the questionable findings of the Renaissance scholar Annius of Viterbo. According to Gelli, Florence was founded long before the time of
Sulla and the
First Triumvirate. Tuscany was the first Italian region to be inhabited, but since the first inhabitants of Italy, who spoke
Aramaic, had probably left no documents, the origin of Florence could not be traced. After the death of Noah and after the various wars among the early inhabitants of Italy there came from Egypt Hercules Libius, the great grandson of Noah. Hercules founded Florence by cutting through Mt. Gonfolina, which allowed the water of the swamps to converge forming a river, and named the river after his coat of arms «Arno», which in Aramaic means «Lion», the symbol of Florence. As to the origin of the Florentine language Gelli maintains, contrary to what we know today, that
Etruscan and
Hebrew are both descendants of Aramaic, one originating in Tuscany, the other in
Palestine. Etruscan, says Gelli, was spoken in Italy long before
Latin, and
Florentine was derived from both these languages. He adds that the nouns in Italian are used according to the Aramaic languages; that is, they are not declined but are distinguished by the preceding article as is the case with Hebrew. The verbs, on the other hand, are conjugated according to the custom of the Latins. Gelli supports his theory by pointing out names of places such as
Carrara,
Arignano,
Arezzo,
Fiesole, by asserting that there are many Florentine words which are derivatives of Aramaic and Hebrew. For example, he says the word «iano» is both Aramaic and Hebrew and is related to the word «vino», which comes from «iain», which in Aramaic means wine. In addition to linguistic sources he also claims as evidence for his hypothesis
folklore material as well as remains of ancient structures such as temples, aqueducts, bridges, tombs, and so forth. In his treatise Gelli emphasizes the cyclical feature of historical development, vaguely foreshadowing
Vico, and maintains that when the civilization of a people has reached its peak it declines to its original state and then starts all over again. He rejects the claim that the Greeks are the fathers of civilization, and endeavors to prove that Italy and other countries were civilized long before Greece. Gelli's theories were passionately received by the French linguist
Guillaume Postel, who, in his essay
De Etruriae regionis originibus, institutis, religione et moribus (1551) claimed that the Etruscan language originates from the Hebrew spoken by Noah and his descendants. == Criticisms ==