The tenth chapter of Sabine Baring-Gould’s Book of Were-Wolves tackles the “Mythological Origin of the Were-Wolf Myth”:
It was not merely a fancied external resemblance between the beast and man, but it was the perception of skill, pursuits, desires, sufferings, and griefs like his own, in the animal creation, which led man to detect within the beast something analogous to the soul within himself; and this, notwithstanding the points of contrast existing between them, elicited in his mind so strong a sympathy that, without a great stretch of imagination, he invested the beast with his own attributes, and with the full powers of his own understanding. He regarded it as actuated by the same motives, as subject to the same laws of honour, as moved by the same prejudices, and the higher the beast was in the scale, the more he regarded it as an equal
He illustrates this with two examples: one, a scene from Iceland’s Finnboga Saga in which Finnbog speaks to a bear; the other an Osage story recorded in J. A. Jones’ Traditions of the North American Indians that deals with anthropomorphized beavers.
The next topic is disconnection between body and soul, prompting Baring-Gould to remark upon cross-species reincarnation in Buddhist belief and reported phenomena involving out-of-body experiences.
After a digression into his etymological theories, Baring-Gould cites a Norse myth in which Loki transforms himself into a bird by wearing a feathered garment, along with shamanic traditions: “Among the Finns and Lapps it is not uncommon for a magician to fall into a cataleptic condition, and during the period his soul is believed to travel very frequently in bodily form, having assumed that of any animal most suitable for its purpose. I have given instances in a former chapter. The same doctrine is evident in most cases of lycanthropy.” He illustrates his points first with a Basque story in which a huntsman and a bear mortally wound each other, allowing the man to breathe his soul into the body of the bear; and then a story from the Indian Panchatantra involving human characters swapping bodies
He then moves on to the broader topic of zoomorphism in mythology, where clouds become sheep and lighting is seen as a serpent. He argues that these early lightning-serpents gave rise to later, more elaborate legends of dragons, and argues that a “similar change has taken place in the swan-maiden and were-wolf myths”. This brings him to the apsaras — bird-women of Indian lore. He finally arrives back at lycanthropy via another being from Indian legend, the Râkschasa:
But it is time for me to leave the summer cirrus and turn to the tempest-born rain-cloud. It is represented in ancient Indian mythology by the Vritra or Râkshasas. At first the form of these dæmons was uncertain and obscure. Vritra is often used as an appellative for a cloud, and kabhanda, an old name for a rain-cloud, in later times became the name of a devil. Of Vritra, who envelopes the mountains with vapour, it is said, “The darkness stood retaining the water, the mountains lay in the belly of Vritra.” By degrees Vritra stood out more prominently as a dæmon, and he is described as a “devourer” of gigantic proportions. In the same way Râkshasas obtained corporeal form and individuality. He is a misshapen giant “like to a cloud,” with a red beard and red hair, with pointed protruding teeth, ready to lacerate and devour human flesh. His body is covered with coarse bristling hair, his huge mouth is open, he looks from side to side as he walks, lusting after the flesh and blood of men, to satisfy his raging hunger, and quench his consuming thirst. Towards nightfall his strength increases manifold. He can change his shape at will. He haunts the woods, and roams howling through the jungle; in short, he is to the Hindoo what the were-wolf is to the European.