Finnish witch selling wind to sailors, Olaus Magnus, c.1555.
Knotcraft
The "Witch's Knot" has been observed in folklore for centuries. Many old beliefs were held about knots, some examples include the belief that the tying of knots could cause impotence in a man, prevent pregnancy in a woman, entangle evil spirits, bind one's will or actions, and even cause death. Witch's knots are most associated, however, with using magic to control the weather. Storms could be raised or calm restored, depending on the intentions of the witch, by binding certain winds in knots. The knot could be tied in rope, thread, cord, or even her own hair. Sailors would purchase favorable winds in the form of knotted cord, understanding it had been tied by witches, both male and female; and were highly prized. The following text is taken from The Holinshed Chronicles (1577), at Oxford University:
"Giraldus noteth a conten|tion betwéene the kings of England & Ireland for the right of this Iland, but in the end, when by a compr [...]|mise the triall of the matter was referred to the liues or deaths of such venemous wormes as should be brought into the same, and it was found that they died not at all, as the like doo in Ireland, sentence passed with the king of England, & so he reteined the Iland. But howsoeuer this matter standeth, and whether anie such thing was done at all or not, sure it is that the peo|ple of the said Ile were much giuen to witchcraft and sorcerie (which they learned of the Scots a nation great|lie bent to that horible practise) in somuch that their women would oftentimes sell wind to the mariners, inclosed vnder certeine knots of thred, with this in|iunction, that they which bought the same, should for a great gale vndoo manie, and for the lesse a fewer or smaller number."
The authors of the Chronicles are essentially just repeating the tale about Manx weather Witches found already in Ranulf Higden's Polychronicon, written in Latin in the mid 14th century. Moreover, the decision by John Trevisa, when translating the Polychronicon into Middle English in 1387 to characterize the weather magic of the women of the Isle of Man as "Witchcraft", is upheld in the Chronicles.
Traditionally, a witch would tie three knots, done in such a way that the wind was bound up in them. In many locations, such as the Isle of Man, the belief held that loosening one knot would bring a South-Westerly wind, two knots a strong North wind, and 3 knots a tempest. In the folklore of Scandinavia and the Shetland Islands of Scotland, some fishermen are said to command the wind this way. In Great Britain, this belief was widespread throughout Cornwall, Shetland, Lewis and the Isle of Man. The term "Witch's Knot" is also used to describe the knotting in a horse's tail or mane, and comes from the same old belief.
Knotcraft was also employed in malefic witchcraft, to do harm, and to act as magical snares. According to a medieval manuscript, a Witch’s Ladder made of a string with nine knots, when hidden, causes a victim to die a slow and wasting death. In Islamic myth the prophet Mohammed was said to have been ensorcelled by an evil man and his daughters who tied 11 knots in a cord, which they then hid in a well. The spell made Mohammed ill, and he wasted away nearly to the point of death. It was only after God sent the angel Gabriel to him, that the hiding place of the cord was revealed. Mohammed recited 11 verses from the Koran over the cord, and as he spoke each, a knot loosened itself, until all were undone and the spell broken. Mohammed calls such magicians’ work “the evil of women who are blowers of knots.”