Basilisk

In European bestiaries and legends, a basilisk is a legendary reptile reputed to be king of serpents and said to have the power to cause death with a single glance. According to the Naturalis Historia of Pliny the Elder, the basilisk of Cyrene is a small snake, "being not more than twelve fingers in length,"[2] that is so venomous that it leaves a wide trail of deadly venom in its wake, and its gaze is likewise lethal; its weakness is in the odour of the weasel, which, according to Pliny, was thrown into the basilisk's hole, recognizable because all the surrounding shrubs and grass had been scorched by its presence. It is possible that the legend of the basilisk and its association with the weasel in Europe was inspired by accounts of certain species of Asiatic snakes (such as the King Cobra) and their natural predator, the mongoose see Euhemeristic accounts below.

The basilisk is called "king" because it is reputed to have on its head a mitre- or crown-shaped crest. Stories of the basilisk show that it is not completely distinguished from the cockatrice. The basilisk is alleged to be hatched by a cockerel from the egg of a serpent or toad (the reverse of the cockatrice, which was hatched from a cockerel's "egg" incubated by a serpent or toad). In Medieval Europe, the description of the creature began taking on features from cockerels.

There is the same power also in the serpent called the basilisk. It is produced in the province of Cyrene, being not more than twelve fingers in length. It has a white spot on the head, strongly resembling a sort of a diadem. When it hisses, all the other serpents fly from it: and it does not advance its body, like the others, by a succession of folds, but moves along upright and erect upon the middle. It destroys all shrubs, not only by its contact, but those even that it has breathed upon; it burns up all the grass too, and breaks the stones, so tremendous is its noxious influence. It was formerly a general belief that if a man on horseback killed one of these animals with a spear, the poison would run up the weapon and kill, not only the rider, but the horse as well. To this dreadful monster the effluvium of the weasel is fatal, a thing that has been tried with success, for kings have often desired to see its body when killed; so true is it that it has pleased Nature that there should be nothing without its antidote. The animal is thrown into the hole of the basilisk, which is easily known from the soil around it being infected. The weasel destroys the basilisk by its odour, but dies itself in this struggle of nature against its own self.

Isidore of Seville defined the basilisk as the king of snakes, due to its killing glare and its poisonous breath. The Venerable Bede was the first to attest to the legend of the birth of a basilisk from an egg by an old cockerel, then other authors added the condition of Sirius being ascendant. Alexander Neckam (died 1217) was the first to say that not the glare but the "air corruption" was the killing tool of the basilisk, a theory developed one century later by Pietro d'Abano.

Theophilus Presbyter gives a long recipe in his book for creating a basilisk in order to convert copper into "Spanish gold" (De auro hyspanico).

Albertus Magnus in the De animalibus wrote about the killing gaze of the basilisk, but he denied other legends, such as the rooster hatching the egg. He gave as source of those legends Hermes Trismegistus, who is credited also as the creator of the story about the basilisk's ashes being able to convert silver into gold: the attribution is absolutely incorrect, but it shows how the legends of the basilisk were already linked to alchemy in 13th century.

Geoffrey Chaucer featured a basilicok (as he called it) in his Canterbury Tales. According to some legends, basilisks can be killed by hearing the crow of a rooster or gazing at itself through a mirror.[5][6] The latter method of killing the beast is featured in the legend of the basilisk living in Warsaw, killed by a man carrying a set of mirrors (the most famous version of the legend was written by Artur Oppman).

Stories gradually added to the basilisk's deadly capabilities, such as describing it as a larger beast, capable of breathing fire and killing with the sound of its voice. Some writers even claimed that it could kill not only by touch, but also by touching something that is touching the victim, like a sword held in their hand. Also, some stories claim its breath is highly toxic and will cause death, usually immediately. The basilisk is also the guardian creature of the Swiss city Basel. As such, the basilisk is a traditional symbol of Basel.

The basilisk was, however, believed to be vulnerable to cockerels; therefore travellers in the Middle Ages allegedly sometimes carried cockerels with them as protection.[7]

Leonardo da Vinci included a basilisk in his Bestiary, saying it is so utterly cruel that when it cannot kill animals by its baleful gaze, it turns upon herbs and plants, and fixing its gaze on them withers them up.

In his Notebooks, he describes the basilisk (an account clearly dependent directly or indirectly on Pliny's (above)):

This is found in the province of Cyrenaica and is not more than 12 fingers long. It has on its head a white spot after the fashion of a diadem. It scares all serpents with its whistling. It resembles a snake, but does not move by wriggling but from the centre forwards to the right. It is said that one of these, being killed with a spear by one who was on horse-back, and its venom flowing on the spear, not only the man but the horse also died. It spoils the wheat and not only that which it touches, but where it breathes the grass dries and the stones are split.
Then Leonardo says the following on the weasel: "This beast finding the lair of the basilisk kills it with the smell of its urine, and this smell, indeed, often kills the weasel itself."