Later in 1742, Casanova entered a seminary to study for the priesthood but was quickly expelled when his further encounters with women are discovered. He took a secretarial position with a Venetian official in Corfu but soon was dismissed. He spent a few months in prison in 1743, but his mother got him out. For the next several years, he went through several more jobs and had one love affair after another, and he fell in with a circle of alchemists and "magicians." In short order he established himself as the head of the group and convinced a rich Venetian to support him in a grand style. For as long as that lasted, he devoted his life to pleasure.
But in 1749 it all crashed down when his extraordinary lifestyle attracted the attention of the Venetian State Inquisitors. Casanova fled Venice on the advice of his patron and began his travels in Europe. There were occasional opportunities to return to his home city, but most of his time was spent in other European capitals where he mixed with high level nobility and academics. In 1753 he returned to Venice where he had additional notorious love affairs and in 1755 he was again imprisoned, ostensibly because of his occult activities, but more likely because of his suspicious contacts with foreign diplomats -- he may have been a spy. He escaped after a few months (his version of the story was published in one of his later books) and fled to Paris, where his recent exploits and his "great escape" gained him access to the highest social circles. He parlayed this into a position on the board of the French state lottery, which made him very rich, and he also continued, over the next several years, to have notorious and financially rewarding relationships with women. During these years he also went on several secret missions for the French government -- perhaps the Venetians were right, and he was a spy.
In succeeding years, Casanova wandered around Europe, making and losing fortunes, had more brushes with the law (sometimes getting out of jail through the influence of his many satisfied ladies), fought a few duels, and began to keep score of his many affairs. He had his ups and downs, had a hard time finding permanent employment, and, at one point, he even considered entering a monastery, but he quickly rejected that idea when he meets another young Baroness.
Throughout the process, Casanova appeared to keep his entire ever-growing list of female friends happy and, also, almost invariably friendly. He didn't "love them and leave them", but rather he kept adding additional names to his list of sometimes companions.
During this period he met all the European intellectual crowd and hobnobbed with the glitteratti. Among them were Mozart and his librettist, Lorenzo da Ponte. And this is where the story of Casanova's long running soap-opera life gets even more confusing.
Casanova collaborated with Da Ponte and Mozart in the writing and production of the Mozart's opera Don Giovanni -- pages of rewrites in all three hands were found among the thousands of pages of documents Casanova left behind. Nobody knows the real extent of Casanova's contribution to the opera, which is an adaptation of the story of Don Juan, a totally fictional character, who, was introduced to literature by Tirso de Molina (the pen name of a Spanish monk, Fray Gabriel Tellez) in 1630, in his verse drama, El Burlador de Sevilla.
The fictional Don Juan, unlike Casanova, did not leave his many conquests smiling, and Tirso's story, like Mozart's adaptation, is a moral tale about human and supernatural vengeance against this kind of unloving malefactor. Although the fictional Don Juan and Casanova had completely opposite viewpoints on women, the stories of the fictional Don Juan and the real Casanova were conflated and were even, to some extent, reversed as a result of the opera and of Casanova's known participation in writing it. In fact, most people still think that Don Juan was a romantic lover and that Casanova was an uncaring rogue. No one can argue that Casanova's promiscuity was excusable, but it is clear that he was at least as interested in making his many women friends happy as in satisfying his own wide ranging desires.
Casanova's fame in his own time was such that he attracted the attention of other famous and infamous people. Among the famous, was Benjamin Franklin when Franklin was in Paris representing the infant American republic.
For many years, he was able to keep up his famous simultaneous correspondences with many different women, but he was having more and more difficulty just making a living. To make ends meet he began writing about his own adventures, probably embroidering and expanding them as he went along. He also had more purely literary output, however, including a translation of Homer's Iliad into Italian verse, commentaries on current philosophy, and theatrical criticism. He was the entrepreneur for a French-language theater group in Venice and also published a French language theater magazine there to drum up business for the theater.
Eventually, his opportunities dwindled even more, and he reluctantly accepted employment as the librarian of a fellow Freemason, Count Joseph Karl Emmanuel von Waldenstein. The pay was adequate, but the position was at the Count's castle in the town of Dux (Duchcov) in what is now the Czech Republic, which did not offer the variety of experiences that Casanova had envisioned for his declining years. With no other prospects on the horizon, Casanova packed himself off to the small town and began the most productive stage of his literary life. He first published the story of his daring escape from the Venetian state prison and quickly followed that with a proto-science-fiction novel, the Icosameron. He produced a series of mathematics treatises (mostly advanced geometry), more philosophical commentaries, satires, biographies and profiles (notably, Catherine the Great of Russia), and, most importantly, twelve volumes of his own autobiography, which he never completed.
In 1797 the Venetian Republic fell, and Casanova contemplated a final return to his ancestral city. But in the spring of 1798 he contracted a urinary infection, apparently having no connection to his previous amorous adventures, and he died in June of that year. On his deathbed he gave the most recent draft of his autobiography to a nephew, and the posthumous publication of his memoirs assured his place in history.
Well, almost. Publishers were so shocked by what they read in the manuscript that only drastically expurgated and Bowdlerized (but still awfully racy) versions were published for more than 150 years. The first unexpurgated English translation was not published until 1962.
A more complete summary of Casanova's life and works is at: http://www.dickinson.edu/~emery/sketch.htm
The Man Who Really Loved Womenis the title of a book by Lydia Flem that attempts to set the record straight on the life, loves, and accomplishments of Casanova. A review of the book is available at: http://www.springharborpress.com/casanova.htm, and the book is available for purchase at: http://www.amazon.co.uk/exec/obidos/ASIN/0374119570/.
Casanova's unexpurgated autobiography, the 1962 Trask translation, is available for purchase at: http://www.amazon.com. Type Trask Casanova in the "search" box.
The famous Auguste Leroux series of 200 color drawings for Casanova's Autobiography is available at: http://let.kub.nl/mousebit/Casanova/indexall12.htm
The Casanova Research Page: http://www.dickinson.edu/~emery/Casanova.htm
Casanova's portrait, painted by his brother in the early 1750's, is at: http://www.italica.rai.it/principali/argomenti/arte/casanova/francescocasanova.jpg
Don Juan and Don Giovanni Links: http://lightning.prohosting.com/~shicoff/Operas/donjuan.html
Tirso di Molina's El Burlador: http://www.langlab.wayne.edu/Romance/SPA6570/tirsoen.htm
Theatrical Don Juans: http://didaskalia.berkeley.edu/supplements/supp1/Gethner.html
Don Juan as Psychopath: http://www.gordonbanks.com/gordon/pubs/donjuan.html
P.S.: Casanova traveled a lot, so he accumulated a number of alternates for the spelling of his name. The most common is the variant that I have used, but even Casanova sometimes spelled it as "Cassanova" or "Chassanova". There are many more variants, but you can find more than anyone except a specialist would want to know by searching the Internet for "Casanova".