On the evening of 19 November 1679, the theatre in Rue Guenegaud is packed.  The King’s Actors are giving the first performance of a most awaited play, La Devineresse, whose authors are Thomas Corneille and the journalist Jean Donneau de Vise, the founder of the Mercure galant.  The plot of this comedy in five acts and in prose is however very simple.  A woman of the world, credulous and infatuated with magic, consults a “devineresse” [fortune teller], to her lover’s despair, and without realizing that she is in reality the victim of the manipulations of a rival who is seeking to prevent their marriage.  Luckily, the lover manages to foil the manoeuvre and, in the last act, confound the trickery of the “devineresse”.  This causes the devil to appear in person to his customer, to definitively dissuade her to marry her lover.  But when the lover is about to kill the said devil (in reality a good bourgeois who has been kind enough to take part in this pretence) with his sword, the devil throws himself at his feet and exclaims:

“Oh! Sir, I’m only a poor fiscal procurer!  What would you gain by killing me?”

The extraordinary success of La Devineresse, with forty-seven successive performances – a considerable figure for the epoch – is not only due to the play’s uncontestable qualities, nor to the perfection of its spectacular sound and visual effects.  If the Parisian public rushes to see it, it is because the play is a direct copy of the news.  Of the judiciary news which will soon become an affair of State and touch so near to the King’s person that Louis XIV will be obliged to personally intervene in the course of justice and impose secrecy on its most serious developments.

In Thomas Corneille’s and Donneau de Vise’s comedy, the famous “devineresse” is called Madame Jobin.  But the spectators are able to recognize under this theatrical name, that of one of the most redoubtable female poisoners in France’s history, Catherine Montvoisin, known as “the Voisin”, whose arrest, on 12 March 1679, sets off such a series of revelations, that no-one is yet able to forsee just where they will go.  Only the lieutenant general de police, the very honest and very prudent Gabriel Nicolas de La Reynie, realizes that he holds the thread of an exceptionally serious case.  And he is the one who, using his power over the theatres of Paris, and his friendship for Donneau de Vise, is the instigator of the play.  In his mind, the aim is to de-mystify “magical” or “alchemical” practices which are very widespread in the capital.  He is well-placed to know that they very often hide appalling criminal activities.  For example, in Act II, Scene ii, Mme Jobin explains to her brother:

“This is how most men are.  They believe in all the stupidities they are told, and, when once they have made up their minds, nothing is then capable of making them change their opinion.  You see, Brother, Paris is the place in the world where there are the most dupes.  The witchcraft of which I’m accused and other things which would appear even more supernatural, need only a lively imagination to invent them and cleverness to use them.  It is through them that people believe in us.  However, magic and devils have nothing to do with it.  Fear blinds those to whom we show these sorts of things, enough to stop them from seeing that we are tricking them.”


But if the Voisin and her ilk are effectively able to mystify everyone by accomplishing rites that are supposed to awaken the heart of a weakening lover or hasten the end of a cumbersome husband, they also possess much less illusionary, and infinitely more redoubtable, means for pleasing the duchesses who do not hesitate to go into the most ill-famed neighbourhoods of Paris to consult them and implore their help…


Cases of poisoning are common occurrences at this epoch.  In the absence of any controls, which will only be instituted in 1682, anybody can very legally obtain all the ingredients entering into the composition of poisons.  Amateur chemists and alchemists are not lacking – all, however, are thankfully not poisoners.  Further, the state of medical knowledge does not allow a really scientific recognition of the symptoms, whether it is a natural or provoked illness, a real or supposed poisoning.  From these confusions issuing from early medicine and chemistry, as they emerge with difficulty from occultism, the Poisons Case, in all its repercussions, is born.

This criminal industry is also favorised by the fact that a whole new quarter of Paris, situated inside the quadrilateral formed by today’s Rues du Temple and de Montmartre, practically escapes police and corporation control.  The “devineresses” exercise their practices there in great numbers, more than four hundred of them, according to the Voisin…  And La Reynie, disabused by the amplitude of the phenomenon, admits:

“Man’s life is publicly put on sale.  It is almost the sole remedy used for all family problems.”


Assisted by Abbot Edmond Pirot, the Marquise de Brinvilliers prepares for death, having confessed all of her crimes.

The interminable criminal serial of the Poisons Case finds its prologue in the not very edifying story of the Marquise de Brinvilliers.  The daughter of a conseiller d’Etat et maitre des requetes, Marie-Madeleine d’Aubray marries, in 1651, Antoine Gobelin, a rich bourgeois from the famous family to whom we owe the manufacture which bears his name.  His fortune is the reason that he is made Marquis de Brinvilliers.  Marie-Madeleine is flighty and leads an exorbitant life-style.  Her bad genie will be an attractive officer of the little Gascony nobility, Jean-Baptiste Gudin de Sainte-Croix, who becomes her lover.  A contemporary will say of him:

“He spoke beautifully of God, in whom he did not believe, and under cover of this pious mask […] he appeared to participate in good deeds and was involved in all the crimes.”

This accomplished rake, as he would have been called in the following century, is, among other things, passionate about chemistry and alchemy.  The making of poisons, however, can sometimes prove to be more expedient than the transmutation of metals…  And Sainte-Croix assuredly does not lack capability in these matters.  A short stay in the Bastille, in 1663, allows him to become acquainted with an “artist in poisons” of Italian origin, Eggidio Exili, and to acquire a knowledge that is usefully completed by the frequentation of Christoph Glaser, an authentic scholar, to whom we owe, in particular, the discovery of potassium sulphate and arsenic chloride.

To be continued.