“Unicorn horns are highly sought after, since possession of one is a sovereign remedy against all poisons. Alternately, a single horn can be used, by an alchemist, to manufacture 2-12 potions of healing. Unicorn horns sell for 1,500 gold pieces or more on the open market. “ — AD&D 2e Monstrous Manual
So I’ve been reading Odell Shepard’s The lore of the unicorn — a treatise on unicorn lore, it should be noted, rather than a treatise on unicorns, as Shepard is principally interested in what writers said about them, how they were used as symbols, and the meaning of the symbolism and legends associated with unicorns. It’s mostly interesting but also dry — it could well have been written in the nineteenth century, and reads like something a country vicar would have compiled in his ample free time … cf. Sabine Baring-Gould. Still, there is some great stuff, and this post harvests some of the triva from an early chapter.
Historically, in the West, unicorn horns (or alicorns — the term has also been applied, incorrectly, to horned pegasi) were highly sought after treasures. Filings from an alicorn were valued at ten times that of gold, by weight; a whole alicorn would be worth double that. As the narwhal tusks which were sold as alicorns can weigh ten kilograms, a whole specimen was a rare treasure to be found only in a king’s treasury or a major cathedral. By the late 16th century, however, nearly every prince had one or part of one as protection against poisoning, which had become a widely practiced art. Deadly diseases like plague were considered to be a kind of poisoning, so to the medieval mind, a cure for poisoning was also a cure for diseases.
The anti-poison property of an alicorn was far from unique, however. A mixture of herbs, minerals, and animal parts called “theriaca” was manufactured as a cure-all, and used both as a salve and ingested medicine, but it was very expensive due to the complexity and time taken to create it, and would be roughly as pricey as alicorn powder. The prince on a budget had many other options when collecting talismans against poison — many of them obtained from animals that were themselves poisonous or thought to be poisonous.
Bezoar stones (concretions of indigestible matter and minerals recovered from the guts of animals) could be dipped into a drink to purify it (bon appetit!)
Cerastes horns (the prominent scales, called “horns,” of the cerastes serpent) were said to weep or sweat in the presence of poison. They were placed on the dining table in artful arrangements to detect poison. Legend had it that the walls of Prester John’s palace were made with a concrete including cerastes horns to prevent any poison from ever entering his demesne. From antiquity, Western scholars held that the cerastes serpent killed its prey by burying itself so that only its poisonous horns were above ground, and passersby who stepped on the horns would die instantly. “Horned serpents” captured the imagination of Westerners from the time of Herodotus, who described them in his History.
Snake tongues would be hung, in bunches, on the table as well, and they too would weep in the presence of poison.
Glossopetra (the “tongue stone,” actually shark tooth fossils) were used in the same manner as snake tongues, and were thought to be the petrified tongues of snakes. They were also credited with warding off the evil eye.
Toad-stones, supposedly recovered from the bodies of toads, were placed in rings to prevent poisoning. Surviving examples of these “toadstones” are probably sting-ray teeth.
Griffin’s claw (usually ibex or buffalo horns) was fashioned into a drinking horn, which would purify any beverage of poison.
Venetian glass or crystal was thought to shatter if any poison were poured into it, and was therefore a popular material for goblets and bowls.
Ruby (also called carbuncle) and amethyst, if placed over poisoned food, would make it inedible and thus prevent a poisoning.
A severed vulture’s foot was thought to clutch in the presence of poison, so candle-holders were fashioned with a claw positioned just so that if it closed, it would snuff out the candle. (In the Middle Ages vultures were believed to be poisonous themselves.)
Terra sigillata was a specially prepared clay from Lemnos, cakes of which were imprinted with a seal depicting Artemis; hence the name. It was used to make amulets which warded off poison, and as an ingredient in theriaca, or as a medicine in its own right.
Walrus tusks and rhinoceros horns were also believed to have some potency in this regard, yet they were were also used to counterfeit alicorns. Some accounts say that special chemical treatments were used to give them the characteristic spiral of a true alicorn. (Certain antelope horns which have a twists or spirals were also imported as alicorns.)
The heyday of the alicorn was in the 14th ro 16th centuries. Belief in their efficacy decline slowly. In Italy and France, belief in the alicorn’s power died out in the 1500s; in England, belief lasted into the 1700s.
One possible echo of the belief in alicorns is the practice of keeping stag horns as trophies. The medieval bestiaries reported that stags ate snakes, and/or that their horns (or the smoke emitted by their burning horns) were fatal to snakes, and for this reason stag horns were hung over doorways to keep out serpents.