Mother Hildegarde, born Hildegarde de Gascogne, is the nun in charge of running L’Hôpital des Anges in Paris, France. She has a dog called Bouton who accompanies her on her rounds and can sniff out sickness.
Mother Hildegarde appears in Dragonfly in Amber, Voyager and The Space between.She has a large harpsichord made of walnut and decorated along the sounding board with small hand-painted flowers sprouting from a twisting vine.

 Mother Hildegarde was played by Frances de la Tour in the series. Photo courtesy of Starz.

Mother Hildegarde was based on a real historical person who lived in the 12th century, rather than the 18th.

St. Hildegard, also called Hildegard of Bingen or Hildegard von Bingen, byname Sibyl of the Rhine, (born 1098, Böckelheim, West Franconia [Germany]—died September 17, 1179, Rupertsberg, near Bingen; canonized May 10, 2012; feast day September 17), German abbess, visionary mystic, and composer.

Hildegard was born of noble parents and was educated at the Benedictine cloister of Disibodenberg by Jutta, an anchorite (religious recluse) and sister of the count of Spanheim. Hildegard was 15 years old when she began wearing the Benedictine habit and pursuing a religious life. She succeeded Jutta as prioress in 1136. Having experienced visions since she was a child, at age 43 she consulted her confessor, who in turn reported the matter to the archbishop of Mainz. A committee of theologians subsequently confirmed the authenticity of Hildegard’s visions, and a monk was appointed to help her record them in writing. The finished work, Scivias (1141–52), consists of 26 visions that are prophetic and apocalyptic in form and in their treatment of such topics as the church, the relationship between God and humanity, and redemption. About 1147 Hildegard left Disibodenberg with several nuns to found a new convent at Rupertsberg, where she continued to exercise the gift of prophecy and to record her visions in writing.

A talented poet and composer, Hildegard collected 77 of her lyric poems, each with a musical setting composed by her, in Symphonia armonie celestium revelationum. Her numerous other writings include lives of saints; two treatises on medicine and natural history, reflecting a quality of scientific observation rare at that period; and extensive correspondence, in which are to be found further prophecies and allegorical treatises. She also for amusement contrived her own language. She traveled widely throughout Germany, evangelizing to large groups of people about her visions and religious insights.

 Hildegard’s alphabet

Hildegard also invented an alternative alphabet. The text of her writing and compositions reveals Hildegard’s use of this form of modified medieval Latin, encompassing many invented, conflated and abridged words. Because of her inventions of words for her lyrics and use of a constructed script, many conlangers look upon her as a medieval precursor. Scholars believe that Hildegard used her Lingua Ignota to increase solidarity among her nuns.

Her earliest biographer proclaimed her a saint, and miracles were reported during her life and at her tomb. However, she was not formally canonized until 2012, when Pope Benedict XVI declared her to be a saint through the process of “equivalent canonization,” a papal proclamation of canonization based on a standing tradition of popular veneration. Later that year Benedict proclaimed Hildegard a doctor of the church, one of only four women to have been so named.

Hildegard’s hagiography, Vita Sanctae Hildegardis, was compiled by the monk Theoderic of Echternach after Hildegard’s death. He included the hagiographical work Libellus or “Little Book” begun by Godfrey of Disibodenberg. Godfrey had died before he was able to complete his work. Guibert of Gembloux was invited to finish the work; however, he had to return to his monastery with the project unfinished. Theoderic utilized sources Guibert had left behind to complete the Vita.

As one of the few prominent women in medieval church history, Hildegard became the subject of increasing interest in the latter half of the 20th century. Her writings were widely translated into English; several recordings of her music were made available; and works of fiction, including Barbara Lachman’s The Journal of Hildegard of Bingen (1993) and Joan Ohanneson’s Scarlet Music: A Life of Hildegard of Bingen (1997), were published.

Sources: https://www.britannica.com/biography/Saint-Hildegard
https://en.wikipedia.org/wiki/Hildegard_of_Bingen
http://outlander.wikia.com/wiki/Mother_Hildegarde
Image from Starz