alchemy—a formula thought to be able to turn base metals into gold or silver. The search for such a formula was certainly a part of the 17th century in all levels of society.
Madame Catherine Voisin was burned alive at the stake for being a witch, but it was possibly Gold Fever that killed her.
Denis Poculot, Sieur de Blessis (sometimes spelled Belsize), is reputed to have been her lover. Whatever their relationship, there was a certainly a significant affiliation between them. He foolishly made the claim to have succeeded in making lead into gold, and was thus more or less held prisoner in the château de Fontenay-en-Brie by the bankrupt Roger de Pardaillan, Marquis de Termes, in an attempt to get Blessis to reveal his secret. (Or, at the least, produce counterfeit money.)
It's likely that La Voisin, who believed in alchemy, invested in Blessis's work. Indignant over his capture, she went to Saint-German-en-Laye to try to put a plea before the King for Blessis's release—and thus began her downfall. (Her mentally unstable daughter claimed she intended to poison the King there.) A few days later, March 12 of 1679, Voisin was arrested coming out of her neighbourhood church after mass.
As to his prisoner, Denis Poculot, Sieur de Blessis, it appears that he was sent to the galleys. He was known for a trick in which mirrors were manipulated in such a way that whoever looked at them died.
And all for the love of gold.
Sandra Gulland is author of The Josephine B. Trilogy and Mistress of the Sun.