One afternoon Eustache Blanchet, in a gallery of the chateau, perceives the Marshal weeping bitterly.  Plaints of supplication are heard through the door of a chamber in which Prelati has been evoking the Devil.

“The Demon is in there beating my poor Francis.  I implore you, go in!” cries Gilles, but Blanchet, frightened, refuses.  Then Gilles makes up his mind, in spite of his fear.  He is advancing to force the door, when it opens and Prelati staggers out and falls, bleeding, into his arms.  Prelati is able, with the support of his friends, to gain the chamber of the Marshal, where he is put to bed, but he has sustained so merciless a thrashing that he goes into delirium and his fever keeps mounting.  Gilles, in despair, stays beside him, cares for him, has him confessed, and weeps for joy when Prelati is out of danger.

“The fate of the unknown sorcerer and of Prelati, both getting dangerously wounded in an empty room, under identical circumstances—­I tell you, it’s a remarkable coincidence,” said Durtal to himself.

“And the documents which relate these facts are authentic.  They are, indeed, excerpts from the procedure in Gilles’s trial.  The confessions of the accused and the depositions of the witnesses agree, and it is impossible to think that Gilles and Prelati lied, for in confessing these Satanic evocations they condemned themselves, by their own words, to be burned alive.

“If in addition they had declared that the Evil One had appeared to them, that they had been visited by succubi; if they had affirmed that they had heard voices, smelled odours, even touched a body; we might conclude that they had had hallucinations similar to those of certain Bicetre subjects, but as it was there could have been no misfunctioning of the senses, no morbid visions, because the wounds, the marks of the blows, the material fact, visible and tangible, are present for testimony.

“Imagine how thoroughly convinced of the reality of the Devil a mystic like Gilles de Rais must have been after witnessing such scenes!

“In spite of his discomfitures, he could not doubt—­and Prelati, half-killed, must have doubted even less—­that if Satan pleased, they should finally find this powder which would load them with riches and even render them almost immortal—­for at that epoch the philosopher’s stone passed not only for an agent in the transmutation of base metals, such as tin, lead, copper, into noble metals like silver and gold, but also for a panacea curing all ailments and prolonging life, without infirmities, beyond the limits formerly assigned to the patriarchs.

“Singular science,” ruminated Durtal, raising the fender of his fireplace and warming his feet, “in spite of the railleries of this time, which, in the matter of discoveries but exhumes lost things, the hermetic philosophy was not wholly vain.