The Cultural Liaison and Investigative Office （CLIO）， a play off the Greek goddess Clio, the muse of history, is my invention, though the United Nations Educational, Scientific and Cultural Organization （UNESCO） is real. One function of that organization is the selection of World Heritage Sites. I thought it ironic to have Nick work for them, while Cotton Malone has a bit of a troubled history with those sites. The reference to the UN member-state agreement in chapter 14 （Section 9, Part C, Paragraph [f]） is my invention, though such a document does exist. The FBI抯 special units charged with art theft recovery exist （chapter 5）。
The Maidens of Saint-Michael and the Congregation of Saint-Luke are fictional, though the latter is somewhat based on the life and work of Plautilla Nelli, one of the first significant female Renaissance artists, along with an organization known as Advancing Women Artists, which champions forgotten works from female artists of the past. The location of the maidens?motherhouse, Abbaye de Saint-Michael, and some of the maidens?history, is modeled after the eleventh-century Abbey of Saint-Martin-du-Canigou, located in southern France, near the Spanish border. The archdiocese of Toulouse is one of the oldest within the Roman Catholic Church, its history and status as a metropolitan archdiocese （chapter 18） accurate. The village of Las Illas （chapter 38） and les Vautours are totally my creation.
The Pontifical Commission for Sacred Archaeology （chapter 26） is real, as are its scope and purpose as detailed within the story. The medieval document quoted in chapter 28 is taken from an actual historical record. Only my addition of les Vautours is fictional. Waterboarding was used extensively by Catholic inquisitors across France and Spain （chapter 7）。 The fleur-de-lys （prologue, chapters 14, 19, 69） is an ancient symbol that has a connection to both the Holy Trinity and the Virgin Mary. The Cross of Occitan on the cover and noted in chapter 22 is constantly mislabeled as a 揅athar cross.?In reality, its history and use are far more secular and predated the Cathars.
Joan of Arc plays a role in the story （chapters 17, 23）。 She is a fascinating historical figure. Much has been written about her, some of it true, some false. We actually know little about her. But her trial and execution in 1431 are well documented （chapters 17, 23）， as is the fact that her ashes were supposedly tossed into a river. Twenty-five years after her death the guilty verdict was reversed （chapter 53） when it became more politically expedient to worship, rather than vilify, her. As to her remains, many ashes and bones have been claimed to be Joan抯。 None have proven as such. The most recent example came in 2007 when a rib bone, supposedly retrieved from the burning pyre in 1431, was discovered to be that of an Egyptian mummy, dating to the third or seventh century BC. Whether any of Joan抯 bones or ashes were actually recovered is totally unknown. So the maidens accomplishing that feat, and Joan herself being a maiden, are both fictional.
The Cathar religion is fascinating. In its simplest form it was a pacifist brand of Christianity, tolerance and poverty its keystones. Woven into that were dualist theories and a total rejection of the material world. M. J. Rose and I explored those beliefs in The Lake of Learning （2019）， a Cassiopeia Vitt novella. This novel allowed further examination. The consolamentum and the melhoramentum （chapter 2） are two essential rituals along the way to becoming a Perfectus, which is the goal of every Cathar. The religion itself supposedly died out six hundred years ago. A bit of art and a few writings are all that have survived. Is it still practiced? Hard to say. But all across the Languedoc the memory of Catharism is actively exploited.
The Gospel of John was important to Catharism （chapters 2, 39）。 The Good Men （as they were known） hated the Old Testament and most of the New. The prayers and replies noted in chapters 2 and 71 are taken from actual surviving text. As mentioned earlier, the slaughter at B閦iers happened, which began the Albigensian Crusade （chapter 4）， but whether the command梩he Lord knoweth them that are his. Kill them all. He will recognize his own梬as issued is a matter of historical debate. But thousands were indiscriminately murdered. The Catholic Church apologized in 2000 for all its past sins （chapter 33）， but, as noted in the story, no specific mention of the Cathars was included. The endura, described in chapter 45, was a part of Cathar beliefs.
Jan van Eyck was truly a Renaissance man long before there was a Renaissance. He did not invent painting with oil, but he did take the technique to new heights, changing art forever. The history noted on him in chapter 37 is true, and the Ghent Altarpiece is still regarded as one of the greatest works of all time.