Yesterday a conman, today a guru?

Two hundred years ago, in August 1795, a notorious Italian conman died a lonely death in San Leo castle, near Rimini. In an ignominious career spanning more than 20 years, Count Cagliostro had blackmailed aristocrats over their sexual indiscretions and sold phoney potions and gemstones to half the Continent's royal courts. He had played a shady role in the pre-revolutionary intrigue at Versailles, and infuriated the Popes by setting up chapters of a strange, quasi-Masonic order all the way from the Atlantic coast to the Urals.

Cagliostro may be largely forgotten in Britain, but in Italy the colourful tale of his rise and fall has always exerted a special fascination, and his blend of charm, showmanship and roguery has become synonymous with one facet of the national character. Historians and novelists have devoted much energy to untangling his mysteries and exposing his dirty tricks.

At least until now. As attention focuses on the bicentennial of his death, Cagliostro is undergoing a strange reassessment. Historians still view him as a charlatan, but they are beginning to consider him in other guises, too: as a political visionary and a founding father of alternative medicine.

Learned newspaper articles are pointing out how he predicted the French Revolution and the downfall of the temporal empire of the Popes. Meanwhile, an exhibition in San Leo castle, where he spent the last four years of his life, focuses on Cagliostro's familiarity with 18th-century herbal and semi-mystical remedies. His darker side is relegated to the background.

So was he in fact a New Age guru of his time rather than a quack?

Although he spent much of his life denying it, Cagliostro was born Giuseppe Balsamo, into a dirt-poor, Sicilian family in 1743. He managed to pass himself off as a man of refinement through sheer charisma. The name Cagliostro came from a distant aunt.

He was educated in a Palermo convent, where he discovered his talent for forgery and learnt the tricks of the medical trade, then headed off to Rome. There he married a beautiful 14-year-old called Lorenza, who was to prove an invaluable asset. Cagliostro would induce rich noblemen to sleep with her, then demand hush money.

Lorenza proved a big selling point for his sect, known as the Egyptian Order. The couple sold elixirs that they said could either halt the ageing process or, for a greater fee, reverse it. Cagliostro himself claimed to be thousands of years old. One of the highlights of his seances was to hear him talk of Roman emperors he had met, and his small-talk with Jesus Christ. "No great personage of the past escaped his friendship," recounts the historian Luigi Barzini. "He was probably the greatest name-dropper in history."

The couple became famous throughout Europe. Their success in France was cut short, however, by a fraud scandal in 1785 over a diamond necklace commissioned for Marie-Antoinette. Everyone assumed that Cagliostro had to be involved somehow, and, although he was eventually acquitted, he was thrown into the Bastille and then ordered out of the country.

It is at this point that accounts of the "true" Cagliostro diverge wildly. According to some, he lost credibility after the necklace affair and audiences were never so gullible again. To boot, the Pope locked him away for the public good. The more recent, revisionist school of thought sees things differently. Cagliostro was not locked up in France for criminal reasons, but because he had prophesied the downfall of the king. Likewise, when he found himself at the mercy of the Vatican a few years later, he was jailed not for fraud but for heresy. Clearly, the revisionists argue, Cagliostro's predictions of revolution and the end of the old order were more alarming to Pope Pius VI than a few dodgy potions.

"This was the twilight of the century of enlightenment. Why else would an adventurer, no more louche than any other, cause foreign ministers across the Continent to lose sleep?" argues Cesare Medail in the Milan newspaper Corriere della Sera.

Everything about Cagliostro treads a fine line between reality and illusion. The great charlatan himself wrote: "A lot of stupid things have been written about me, but you will never discover the truth because nobody knows it." It may havebeen the most straightforward thing he ever said.