The room seemed to be bending of its own accord. I tried to counteract the distortion with sheer effort, that Leonardo would not think me weak. I made my voice as steady as I could. “Do you believe the man was poise, poised—poisoned—with wine in his blister beetles?”
“My dear Francesco, I believe you have been ‘poised’ by wine yourself! Did you know that potions made from blister beetles—cantarella—is a favorite of the Borgia family?”
My eyes refused to focus.
“Lucrezia is said to keep cantarella hidden in a ring with a secret compartment. I cannot vouch for that, but her brother Cesare was a well-known poisoner.”
Cantarella, or cantharidin, is secreted by the male blister beetle as a “gift” to the female during copulation. After mating. the female covers her eggs with the toxic substance to polish off any unsuspecting predators.
Historically, cantharidin was used as an aphrodisiac—the famous Spanish fly that we teenagers used to whisper about. More often it’s used as a treatment for warts by medical doctors. But taken internally in large doses, the stuff is deadly. The U.S. classifies it as an “extremely hazardous substance.”
Poison was the weapon of choice among Renaissance nobility. Leonardo’s benefactor, Ludovico Sforza, poisoned his own nephew in order to steal the ducal crown. In the biography Leonardo da Vinci, Walter Isaacson notes that “...Ludovico was a choirboy compared with Leonardo’s next patron, Cesare Borgia—murder, treachery, incest, debauchery, wanton cruelty, betrayal, and corruption” were all part of his arsenal of dominance.
When Cesare was on a mission to eliminate the rival families of the Orsini and Colonna, he and his father Pope Alexander VI stopped in for dinner with Cardinal Adriano at his palace outside Rome. All three fell ill. Cesare and the cardinal recovered, but Cesare’s father died. While there’s no evidence to prove treachery, some have suggested that the pope had been accidently poisoned by Cesare—from a dose of cantarella intended for Cardinal Adriano. He may have mixed up the flasks, like in the The Court Jester: “The pellet with the poison’s in the vessel with the pestle; the chalice from the palace has the brew that is true.” You’re welcome.