Unicorn’s horn

As men to try the precious unicorn s horn Make of the powder a preservative circle And in it put a spider, so these arms Shall charm his poison, force it to obeying And keep him chaste from an infected straying. 

The unicorn s horn, another item of the dirt pharmacy associated with Paracelsus and the new magic medicine, was meant to be so powerful an antidote to poison that the venomous spider would be repelled by, and find itself unable to cross, the boundary of a circle made from its powder.37 Isabella s simile, in this context, is curious the infected straying to which she refers seems to associate the feared poison with an external contaminant, presumably Vittoria, yet the venomous spider seems to be Brachiano himself. Isabella seems more concerned with containing Brachiano s poison inside her circle than with keeping out that of Vittoria. 

In medieval times it was thought that the legendary unicorn s single horn could neutralize poisons. Such a scene is portrayed in The Unicorn is Found tapestry, one of the famous series completed 1495-1505 in the Netherlands, and now in the Cloisters Collection of the Metropolitan Museum of Art. Serpents were believed to pollute waters with their poisons. In this tapestry the hunters watch as the unicorn cleanses a poisoned stream with his horn. 

Many bulls have compassed me strong bulls of Bashan have beset me round. They gaped upon me with their mouths, as a ravening and a roaring lion...Save me from the lion s mouth for thou hast heard me from the horns of the unicorns. 

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