The Affair of the Poisons: When the French King Danced with the Devil
Blood on the Altar of Versailles
Imagine standing in the shadows beneath Paris. Candlelight flickers. A naked woman lies spread across an unholy altar, black candles clutched in her extended hands, a chalice positioned between her thighs. The stench of incense mingles with something fouler. An old priest in silver-embroidered vestments murmurs backwards prayers. An assistant glides forward carrying an infant.
One swift motion across the throat. A stifled cry. Warm blood streams into the chalice and spills across pale skin.
This wasnât fiction. This happened in the 1670s. The woman on the altar? Madame de Montespan, the official mistress of Louis XIV, the Sun King himself. And this wasnât the only child who died this way.
Welcome to the Affair of the Poisons, the most spectacularly depraved scandal in French history.
The Sorceress of Paris
Catherine Deshayes Monvoisin was born around 1640, and from childhood she learned to read palms and tell fortunes. She married a jeweler named Antoine Monvoisin in her teens, and they had at least three children. Life was comfortable until Antoineâs business collapsed. Catherine refused to return to poverty. Sheâd tasted something better.
So she became La Voisin. The Neighbor.
She set herself up as a fortune teller, using cold reading skills to convince aristocratic clients she possessed genuine powers. She spent lavishly on atmosphere. Crimson velvet robes embroidered with golden eagles. Darkened consultation rooms. Theater for the desperate rich.
But fortune telling was just the start.
La Voisin employed priests to perform Satanic rituals in catacombs beneath her home, where naked women served as altars while priests performed inverted Catholic masses, spilling the blood of newborn babies into chalices as participants prayed to dark powers. She sold aphrodisiacs, love potions, and abortion services. She learned how to give women abortions, a procedure in high demand when strict Catholicism collided with aristocratic appetites for debauchery.
And she sold poison.
Lots of poison.
They called them âinheritance powders.â
The Kingâs Mistress Makes a Deal
In the spring of 1667, Madame de Montespan sought out La Voisin with a desperate purpose: she wanted to steal the king from his current mistress, Louise de la ValliĂšre. Louis XIV had already told his brother he wasnât interested in AthĂ©naĂŻs. Sheâd tried for over a year to seduce him. Nothing worked.
So she turned to darker methods.
La Voisin created a love potion made from bats, toads, blood from dead infants, ground human bones, and herbs. Montespan was to administer it to the king daily until it worked. How she would slip it to him was left to her ingenuity.
Whatever Montespan did, it worked. She became the kingâs official mistress, bearing him seven illegitimate children over the next decade. But power is paranoia. Love is control. And Montespan wasnât taking chances.
Around 1672-1673, Montespan participated in at least three black masses conducted by the defrocked priest AbbĂ© Ătienne Guibourg. Guibourg was the sacristan of Saint-Marcel church at Saint-Denis and claimed to be the illegitimate son of Henri de Montmorency. He knew chemistry. He knew ritual. Heâd traded his collar for something darker.
Montespan lay across the altar on her back, her body perpendicular to its length with knees drawn up, a pillow supporting her head and holding candlesticks with black candles in her extended arms, a cross placed between her breasts and the chalice between her thighs, while Guibourg stood between her knees.
During the ritual, Guibourg intoned: âAstaroth, Asmodeus, princes of friendship and love, I invoke you to accept the sacrifice, this child that I offer you, for the things I ask of you. They are that the friendship and love of the King and the Dauphin may be assured to me, that I may be honoured by all the princes and princesses of the Court, that the King deny me nothing I ask whether it be for my relatives or for any of my household.â
Three masses were performed at intervals, with the second taking place in a tumble-down house at Saint-Denis and the third in a house at Paris, where Guibourg was taken blindfolded. And in due course, Montespan regained her hold over Louis XIV.
But the kingâs eye wandered. It always did. When Louis XIV entered into a relationship with AngĂ©lique de Fontanges in 1679, Montespan called for La Voisin and asked her to have both the king and Fontanges killed.
La Voisin hesitated. Killing commoners was one thing. Regicide was quite another. But she was eventually convinced.
The Web Unravels
Everything started to collapse in 1677.
A woman named Magdelaine de La Grange was arrested and charged with poisoning her lover. Facing execution, she claimed she had information about crimes involving prominent people. The police chief, Gabriel Nicolas de la Reynie, started investigating. What he found horrified him.
Authorities rounded up fortune tellers and alchemists suspected of selling not only divinations and aphrodisiacs, but âinheritance powders,â and under torture they confessed and gave authorities lists of their clients.
In January 1679, the successful fortune teller and poisoner Marie Bosse was arrested, and the investigation revealed a network of fortune tellers in Paris dealing in poison distribution. Marie Bosse was a rival of La Voisin. She talked.
On March 12, 1679, La Voisin was arrested outside Notre-Dame de Bonne-Nouvelle after attending mass, just before her planned meeting with Catherine Trianon.
The king was terrified. His mistress was implicated. Half his court might be involved. Louis XIV ordered the opening of a special court to handle the case: the Chambre Ardente, or Burning Court, so called because it was reminiscent of medieval trials usually set in dark rooms dimly lit by torches. The court held 210 sessions at the Arsenal in Paris, issued 319 writs of arrest, and sentenced 36 persons to death.
The Body Count
How many people died because of La Voisinâs network?
Her purported organization of commissioned black magic and poison murder was suspected to have killed 1,000 people, but itâs believed that upwards of 2,500 people might have been murdered.
Many of the victims were infants and children used as ingredients for ritual magick.
There are conflicting accounts of exact numbers - though upon La Voisinâs arrest, investigators allegedly discovered the corpses of 2,500 infants buried in her yard, allegedly sacrificed the same way as in Guibourgâs ritual, with La Voisin having paid prostitutes for their infants for use in the rituals.
However, historian Anne Somerset disputes this claim and states thereâs no mention of the garden being searched for human remains. Marie Bosse claimed that fetuses aborted late in pregnancy were burned in a furnace at the house of La Voisin and buried in her garden, but Louis XIV gave the order that the abortion aspect should not be pursued further, so this remains unconfirmed.
The truth? Weâll never know. Louis XIV made sure of that.
Drunk on the Way to Hell
La Reynie knew La Voisin loved wine and had multiple lovers. So he kept her drunk during questioning. Questioned while intoxicated, La Voisin claimed that Montespan had bought aphrodisiacs and performed black masses with her to gain and keep the kingâs favor over rival lovers.
The confessions kept coming. Names tumbled out. The scandal threatened to consume the entire court.
La Voisin was sentenced to death for witchcraft and poisoning and burned at the stake on February 22, 1680.
On her way to her execution, she reportedly pushed away the priest, and when fastened on the stake, she desperately pushed away the hay piled up around her. Madame de Sévigné, the famous letter writer, described how La Voisin swore and struggled violently, fighting against the flames five or six times as the fire refused to catch properly.
She burned in the Place de GrĂšve, the main execution ground of Paris, in front of cheering crowds. Madame de SĂ©vignĂ© wrote that she still knew âa thousand pleasant little tales like that one,â suggesting Parisians viewed death as an amusing show rather than a deterrent.
The Royal Coverup
In July 1679, La Voisinâs daughter Marguerite Monvoisin revealed her motherâs connection to Montespan, which was confirmed by statements from other accused. The king faced an impossible situation. His former mistress, mother of his illegitimate children, was implicated in infant sacrifice, poisoning attempts, and conspiracy to murder him.
This caused Louis XIV to eventually close the investigation, seal the testimonies, and place the remaining accused outside the public justice system by imprisoning them under a lettre de cachet.
No trial. No publicity. Just quiet imprisonment.
In 1709, his life drawing to a close, Louis XIV had the registers of the Chambre Ardente burned, perhaps a desperate gesture to keep his luminous reign unspoiled or to preserve the legacy of his former mistress. The truth was erased. Or at least, he tried.
Guibourg was arrested in 1680 and confessed to performing black masses and other crimes, receiving a sentence of life imprisonment, and died in prison in January 1686.
What Really Happened?
Hereâs what we know for certain: Between 1677 and 1682, the Affair of the Poisons implicated prominent members of the aristocracy on charges of poisoning and witchcraft, reaching into the inner circle of the king and leading to the execution of 36 people.
We know La Voisin ran a criminal network. We know she sold poisons. We know she performed abortions. We know black masses were conducted.
But how much of the infant sacrifice testimony was true? How involved was Montespan really? Did she merely buy love potions, or did she lie naked on an altar while babies were slaughtered above her?
There was no evidence beyond confessions, but bad reputations followed these people afterwards.
The police chief La Reynie observed grimly: âThe enormity of their crimes proved their safeguard.â They were too powerful, too close to the king, too dangerous to fully expose.
The Legacy of Horror
The Affair of the Poisons revealed something rotten at the heart of the Age of Enlightenment. While philosophers wrote about reason and progress, the aristocracy of Franceâs most powerful court was consulting fortune tellers, buying poisons, and allegedly sacrificing infants to demons.
On July 31, 1692, an edict banished soothsayers, diviners, and horoscope readers from the Kingdom, severely punished superstitious practices and so-called magic (now considered pure charlatanism and sacrilege), and regulated the trade in toxic products, herbs, snakes, toads, and vipers, reserving the right to have laboratories solely for apothecaries and professors of chemistry.
The scandal forced Louis XIV to confront uncomfortable truths. His magnificent court, the envy of Europe, was a nest of murderers. His mistress had possibly participated in ritual child sacrifice. His absolute power couldnât control the darkness lurking in every gilded corner of Versailles.
La Voisin died swearing and fighting against the flames. But her real legacy? She pulled back the velvet curtain on the ugliest aspects of power, vanity, and desperation. She showed that when people have everything except what they want most, theyâll make deals with anyone, even the Devil himself.
And sometimes, the Devil takes his payment in infant blood.
The full truth of the Affair of the Poisons died with Catherine Monvoisin and was buried deeper when Louis XIV burned the records. Weâre left with fragments, confessions extracted under torture and wine, and the testimony of accomplices trying to save their own skins. But even allowing for exaggeration and coerced confession, what remains is dark enough to haunt. In the golden halls of Versailles, beneath the crystal chandeliers and classical art, something monstrous was happening. And the Sun King knew it.