In 1786, Casanova published 'Le soliloque d'un penseur', in which he
speaks of Saint-Germain and of Cagliostro. On the 23rd December 1792,
Zaguri wrote Casanova that Cagliostro was in prison at San Leo. "Twenty
years ago, I told Cagliostro not to set his foot in Rome, and if he had
followed this advice he would not have died miserably in a Roman prison."
In January 1788, appeared 'Icosameron' a romance in five volumes,
dedicated to Count Waldstein, which he describes as "translated from the
English." This fanciful romance, which included philosophic and
theological discussions, was the original work of Casanova and not a
translation. It was criticized in 1789 by a literary journal at Jena.
Preserved at Dux were several manuscripts with variants of 'Icosameron'
and also an unpublished reply to the criticism.
In 1788 Casanova published the history of his famous flight
from "The Leads". An article on this book appeared in the German
'Litteratur-Zeitung', 29th June 1789: "As soon as the history was
published and while it was exciting much interest among us and among our
neighbors, it was seen that other attempts at flight from prisons would
make their appearance. The subject in itself is captivating; all
prisoners awake our compassion, particularly when they are enclosed in a
severe prison and are possibly innocent . . . . The history with which we
are concerned has all the appearances of truth; many Venetians have
testified to it, and the principal character, M. Casanova, brother of the
celebrated painter, actually lives at Dux in Bohemia where the Count
Waldstein has established him as guardian of his important library."
In July 1789 there was discovered, among the papers of the Bastille, the
letter which Casanova wrote from Augsburg in May 1767 to Prince Charles
of Courlande on the subject of fabricating gold. Carrel published this
letter at once in the third volume of his 'Memoirs authentiques et
historiques sur la Bastille'. Casanova kept a copy of this letter and
includes it in the Memoirs.
In October 1789, Casanova wrote M. Opiz that he was writing to a
professor of mathematics [M. Lagrange] at Paris, a long letter in
Italian, on the duplication of the cube, which he wished to publish. In
August 1790, Casanova published his 'Solution du Probleme Deliaque
demontree and Deux corollaires a la duplication de hexadre'. On the
subject of his pretended solution of this problem in speculative
mathematics, Casanova engaged with M. Opiz in a heated technical
discussion between the 16th September and 1st November 1790. Casanova
sought vainly to convince Opiz of the correctness of his solution.
Finally, M. Opiz, tired of the polemics, announced that he was leaving on
a six-weeks tour of inspection and that he would not be able to occupy
himself with the duplication of the cube for some time to come. On the
1st November, Casanova wished him a pleasant journey and advised him to
guard against the cold because "health is the soul of life."
In 1797, appeared the last book published during Casanova's lifetime, a
small work entitled: 'A Leonard Snetlage, docteur en droit de
l'Universite de Goettingue, Jacques Casanova, docteur en droit de
l'Universite de Padoue'. This was a careful criticism of the neologisms
introduced into French by the Revolution. In reference to Casanova's
title of "Doctor," researches by M. Favoro at the University of Padua had
failed to establish this claim, although, in the Memoirs Casanova had
written:
"I remained at Padua long enough to prepare myself for the Doctor's
degree, which I intended to take the following year." With this devil of
a man, it is always prudent to look twice before peremptorily questioning
the truth of his statement. And in fact, the record of Casanova's
matriculation was discovered by Signor Bruno Brunelli.