This led her to meet the Count of St. Germain, with whom she worked for 4 years on trying to find the philosopher's stone, an endeavour which cost her nearly one hundred thousand écu.

A few years later, she met the Count of Cagliostro, who made her spend four to five hundred thousand francs in an attempt to summon the spirits of Paracelsus and Moïtomut, who were supposed to reveal to him the last of the Grand Arcanum works.

"She ended up falling into the hands of another Italian impostor, named Casanova, who had the delicacy to never ask her for money, but only for expensive gemstones in order to form constellations," said the Marquise de Créquy.

Casanova proposed to impregnate her with herself during a magical threesome ceremony, so that she might give birth to a male (supposed to hold more occult powers), in which her soul would be transmitted through childbirth.

This is evoked several times by Casanova in his memoirs, as well as by Caroline of Hesse (1721-1774, wife of Louis IX of Hesse-Darmstadt), who wrote on 7 April 1758 "There's a Madame d'Urfé in Paris, clever woman, but who believes herself in communication with sylphs and genies."