Humans dread poison—and yet they are transfixed by the idea of premeditated poisoning. Roman citizens of every class used poison to assassinate their enemies—often at the dining table. But it was during the Medieval period that the cult of poison reached new heights. Poison became the method of choice for eliminating family, church, or state adversaries. Medieval apothecaries did a brisk business selling an expanded list of purportedly lethal items (including cat brains and menstrual blood), along with their antidotes.
Although poisoning was believed to be a prevalent practice, rumors and plots were even more ubiquitous. Given the standard of hygiene during period, it would have been difficult to distinguish between intentional and unintentional poisonings. And although many things were allegedly poisoned—clothes, books, and even flowers—poisoned food and wine produced the most dread.
According to Maimonides’ Treatise on Poisons and Their Antidotes (c. 1198): “One does not take any [bread] from those whom he suspects of a trickery but only from those he firmly trusts. It is not far-fetched or difficult to place poison in a simple or complex food and succeed with this intention with any food or beverage taken. Even if it doesn’t kill, it will cause harm and deliverance rests only in the hands of God.”
The wealthy and powerful employed tasters to sample their food. Others purchased what were believed to be powerful anti-poisons: gems such as diamonds, emeralds, and coral—among the real gemstones—and bezoars, unicorn horns (narwhal tusks), toadstones, and snake’s tongues (fossil shark teeth)—among the more fanciful.
According to Kuntz (1913): “Bueus asserts that if the weight of eighty barley-corns of its [emerald’s] powder were given to one dying from the effects of poison, the dose would save his life. The Arabs prized emeralds highly for this purpose, and Abenzoar states that, having once taken a poisonous herb, he placed an emerald in his mouth and applied another to his stomach, whereupon he was entirely cured.”
As it was noted that these remedies were frequently ineffectual, an explanation was sought in the fact that spurious stones were often used, the apothecaries either not having the knowledge to recognize the genuine stones, or being moved by a desire to profit by the substitution of some inferior substance. Hence physicians were warned to be on their guard against such deceptions, and only to employ thoroughly trustworthy apothecaries for the compounding of their prescriptions. ~Kuntz (1915)
Bezoar stones come from indigestible material that accumulates in the digestive tract of ruminants. Bezoars were worn in rings or placed in goblets to protect against poison. Occasionally, large bezoars formed the drinking vessel itself. Rudolf II was known to own several exceptionally large vessels, which were trimmed in gold.
As an antidote for any poison which may have been administered, nothing more excellent than the bezoar stone can be had. ~Anselmus de Boodt
Toadstones, calcified objects from the stomachs or heads of toads, were said to work like bezoars. A 1586 inventory of Mary I of Scotland’s possessions includes just such a stone, which is listed as: “a little silver bottle containing a stone medicinable against poison.”
At times, several of these of these Medieval anti-poisons were combined on a single ornament called an arbre d’épreuve (proving tree) or a languier (serpent’s tongue). This item, often made of precious metals, had suspended from it ten or more stones with a capacity to detect or neutralize poison. It was believed that the stones would sweat, change color, or exhibit some other phenomenon if poison was present in the food being served.
King (1870) quotes a 14th-century inventory that included “a great languier of silver-gilt” that belonged to Louis I, Duke of Anjou: “[it] has several branches, at the end whereof are fifteen serpent’s tongues, and between the tongues, at the end of other branches, be stones of divers colours; also there be dispersed about the said tree several stones hanging from little chains of silver and gold; and in the middle of the said tree is a great white cameo, and around this are four other stones, to wit, two garnets and two green stones…”
In Italy, the proving tree would have been placed on a sideboard known as a credenza. The act of “credenza” (credence, trustworthiness, or belief) involved the tasting of food and drink by a servant in order to test for poison. The name passed to the room where the act took place and then onto the item of furniture.