Catherine DESHAYES, known as la VOISIN (1640–1680) Midwife and poisoner, central figure in the Poison Affair. L.A., with signature on the back, 1679; 1¼ pages, in-4 (crinkled paper, creases, slight foxing, and a small tear; framed on both sides). A very rare autograph letter by La Voisin, a piece of evidence in the Poison Affair. It is evident that La Voisin was virtually illiterate. “ Madam, I believe you have surely been told that I have been longing to have the pleasure of seeing you, but my circumstances are so unfortunate that I have not yet been able to meet with you. In the meantime, I am sending you my niece, and you will give her what you know in writing—what is necessary. Farewell; I send you my regards and remain yours.” This letter was presented to Voisin during the investigation of the Poison Affair by the “Chambre ardente,” as indicated by the note on the reverse: “Following the interrogation of Catherine Deshayes on this day, the 14th of August 1679,” signed by Voisin herself as “Deshayes”; and by the two rapporteurs of the Poison Affair: Lieutenant General of Police Gabriel-Nicolas de LA REYNIE (1625–1709) and Councilor of State Louis BAZIN de Bezons (1636–1700).