Count Cagliostro spent his boyhood wandering the Near East. He boasted a noble lineage, learned the secrets of Egyptian Freemasonry, and could heal the sick, convert base metals into gold, predict the future, and commune with the dead. He was, of course, a fraud, but as Iain McCalman argues in his new biography The Last Alchemist, he was the sort of fraud who almost couldn't help but thrive in the Age Of Reason. As rationality became a supreme virtue, it cast a long shadow in which con artists, spiritualists, and secret societies thrived. Cagliostro fit into each of these niches: Born humbly in Sicily, he turned a small-time trade in potions, deceptions, and the occasional pandering of his wife Seraphina into a lifetime occupation. The more believers he attracted, the more his larger-than-life persona became indistinguishable from the man beneath it. And the time was right to attract scores of believers, particularly once Cagliostro hitched his wagon to the more mystical strands of Freemasonry. While the prevailing intellectual trends looked for a universe founded on rational laws, Cagliostro picked up where reason left off, promising lost mystical secrets known only to him. He profited from it, but part of what makes Cagliostro such a fascinating figure is that he had more than profit in mind, founding free healing clinics for the poor that, for a while, gave him a base of popular support no matter how many famous and powerful figures he alienated. (By the time he died in an Italian prison in 1795, the list included Casanova, Catherine The Great, Marie Antoinette, and Pope Pius VI.) How did a simple swindler rise to a position so powerful that one extremely conspiracy theory credited him with instigating the French revolution? McCalman's detailed account refrains from too much theorizing, leaving his subject a bit of a mystery, but in many respects, that's an unavoidable and fitting conclusion. Whether with deception or with magic, Cagliostro somehow filled a need for belief beyond reason.