François Barbé-Marbois, Chargé d'affaires of the French convoy. Schrepfer's real name was soon found out and reports of his supernatural powers reached Karl von Sachsen. The Prince decided to seek reconciliation and personally visited Schrepfer to apologize for the chastising he had ordered not long before. Schrepfer accepted the apologies and reluctantly promised to come and summon a spirit at the palace at the Prince's repeated requests. The Prince chose the spirit of his uncle, Governor Johann Georg, Chevalier de Saxe to be evoked, partly in the hope that this would reveal where in the palace the Governor had hidden the large sums of money that he supposedly had amassed. At the appointed night a company of 19 witnesses had gathered in the great gallery of the palace. All windows and doors were secured and Schrepfer offered punch to strengthen the nerves. Some readily accepted the drink, while others declined in order to keep a clear mind. Schrepfer started the ceremony, kneeling in a corner of the gallery. It took a long time before anything happened and Schrepfer worked himself into a violent sweat and almost in convulsions. Then a loud clatter was heard outside all of the windows and a sound followed which resembled a glass harmonica. According to Schrepfer this announced the arrival of good, protecting spirits. Not long after frightful yelling was heard, which Schrepfer attributed to the malignant spirits necessary for the commencement of the séance. He continued his evocations until a door opened with violence and a black orb rolled into the room, invested with smoke. Amidst the smoke a human face could be seen, resembling the Chevalier de Saxe. It called out loudly and angry; "Karl, was wolte du mit mich?" (Karl, what do you want of me, why do you disturb me?"). The spectators were all petrified and nobody dared to check its incorporeal nature. The Prince threw himself on his knees and called on God for mercy. Others asked Schrepfer to make the apparition disappear. It seemed to take an hour before Schrepfer's invocations dismissed the spirit, only to burst back in when the spectators had just started to feel relieved of the horror. Schrepfer's reiterated exorcisms at last expelled the apparition for good and left the spectators in awe of Schrepfer's supernatural powers. The Elector soon heard about the event and forbade repetition. In secret Prince Karl and Schrepfer kept on