Various methods for becoming a werewolf have been reported, one of the simplest being the removal of clothing and putting on a belt made of wolfskin, probably as a substitute for the assumption of an entire animal skin (which also is frequently described). In other cases, the body is rubbed with a magic salve. To drink rainwater out of the footprint of the animal in question or to drink from certain enchanted streams were also considered effectual modes of accomplishing metamorphosis. The 16th century Swedish writer Olaus Magnus says that the Livonian werewolves were initiated by draining a cup of specially prepared beer and repeating a set formula. Ralston in his Songs of the Russian People gives the form of incantation still familiar in Russia.
In Italy, France and Germany, it was said that a man could turn into a werewolf if he, on a certain Wednesday or Friday, slept outside on a summer night with the full moon shining directly on his face.
In other cases, the transformation was supposedly accomplished by Satanic allegiance for the most loathsome ends, often for the sake of sating a craving for human flesh. "The werewolves", writes Richard Verstegan (Restitution of Decayed Intelligence, 1628),
are certayne sorcerers, who having annoynted their bodies with an ointment which they make by the instinct of the devil, and putting on a certayne inc haunted girdle, does not only unto the view of others seem as wolves, but to their own thinking have both the shape and nature of wolves, so long as they wear the said girdle. And they do dispose themselves as very wolves, in worrying and killing, and most of humane creatures.
Such were the views about lycanthropy current throughout the continent of Europe when Verstegan wrote.
The phenomenon of repercussion, the power of animal metamorphosis, or of sending out a familiar, real or spiritual, as a messenger, and the supernatural powers conferred by association with such a familiar, are also attributed to the magician, male and female, all the world over; and witch superstitions are closely parallel to, if not identical with, lycanthropic beliefs, the occasional involuntary character of lycanthropy being almost the sole distinguishing feature. In another direction the phenomenon of repercussion is asserted to manifest itself in connection with the bush-soul of the West African and the nagual of Central America; but though there is no line of demarcation to be drawn on logical grounds, the assumed power of the magician and the intimate association of the bush-soul or the nagual with a human being are not termed lycanthropy. Nevertheless it will be well to touch on both these beliefs here.
The curse of lycanthropy was also considered by some scholars as being a divine punishment. Werewolf literature shows many examples of God or saints allegedly cursing those who invoked their wrath with werewolfism. Those who were excommunicated by the Roman Catholic Church were also said to become werewolves.
The power of transforming others into wild beasts was attributed not only to malignant sorcerers, but to Christian saints as well. Omens Angeli, boni et Mali, ex virtute naturali habent potestatem transmutandi corpora nostra ("All angels, good and bad have the power of transmutating our bodies") was the dictum of St. Thomas Aquinas. St. Patrick was said to have transformed the Welsh king Vereticus into a wolf; Natalis supposedly cursed an illustrious Irish family whose members were each doomed to be a wolf for seven years. In other tales the divine agency is even more direct, while in Russia, again, men supposedly became werewolves when incurring the wrath of the Devil.