Sabine Baring-Gould’s book on werewolves is one of the thinnest volumes ever published by Valdemar, a publishing house specializing in horror stories. But The Book of Werewolves is not fiction, but an essay on lycanthropy published in 1865 and written from a rational, quasi-scientific point of view. Yet he doesn’t ignore the mythology that has given rise to so many stories about werewolves throughout the ages. Baring-Gould’s Book of Werewolves is a study of folklore in which Lovecraft’s cosmic horror – the irrational – is combined with the kind of reality physicist Richard Feynman had in mind when he said the truth is stranger than fiction.

But the most disturbing thing about this edition of Baring-Gould’s book is undoubtedly the cover. It represents a woman with a lupine face covered with hair. She is holding a piece of paper that appears to be a birth certificate, as if confirming her humanity. This is Antonietta Gonsalvus, daughter of Petrus Gonsalvus (alias Pedro González), better known as the Wild Gentleman of Tenerife.

Petrus Gonsalvus suffered from hypertrichosis, a genetic alteration which his daughter Antonietta inherited and which made her an exotic specimen at the royal court. Antonietta’s portrait was painted by Lavinia Fontana, court painter to Pope Clement VIII and one of the most famous women of her time. Petrus, his father, was born on the island of Tenerife (Spain) in 1537. At the age of 10, he was taken to France, where he became the protege of King Henry III.

Petrus Gonsalvus’ condition made him a celebrity at the king’s court, a living allegory of the monarch’s political power – King Henry III towers over the beast and thus rules the world. The metaphor of the werewolf tamed by the king represented the triumph of good over darkness, according to Hebrew mythology in which the wolf is Satan’s favorite animal form. Thus, the devil disguised as a wolf becomes the enemy of the lamb, the figurative form of Jesus Christ. It took a long time for the so-called werewolf syndrome to be understood as a genetic dermatological disorder, a rare disease that causes the fine lanugo hairs found on newborn babies to continue growing on the body for the rest of a person’s life.

Petrus Gonsalvus was the first documented case of hypertrichosis. In 1573 he married a Parisian named Catherine, and the two became legendary. Two hundred years later, the couple will inspire the story of Beauty and the Beast, by Marie Leprince de Beaumont. Petrus and Catherine had three sons and three daughters, including Antonietta, who inherited the genetic condition like most of her siblings. But it was Antonietta who graced the cover of the Spanish edition of The Book of Werewolves, in which theologian Baring-Gould traced the tradition of werewolves from classical antiquity to modern culture, demonstrating that ” under the veil of mythology hides a logical reality”, just as “a grain of truth is hidden” under every superstition.