Question: In what year was the abbess who wrote the biography of Bertha of Bingen born?

Context articles: The Story of a Great Schoolmaster
Bertha of Bingen
Hildegard of Bingen
Clementia Killewald
Jiko Linda Cutts
Bertha Vyver
Kitty Brazelton
Deborah Baker
Beverly Mayne Kienzle
Disibodenberg

The Story of a Great Schoolmaster is a 1924 biography of Frederick William Sanderson (1857-1922) by H. G. Wells.
 It is the only biography Wells wrote.
 Sanderson was a personal friend, having met Wells in 1914 when his sons George Philip ('Gip'), born in 1901, and Frank Richard, born in 1903, became pupils at Oundle School, of which Sanderson was headmaster from 1892 to 1922.
 After Sanderson died while giving a lecture at University College London at which he was introduced by Wells, the famous author agreed to help produce a biography to raise money for the school.
 But in December 1922, after disagreements emerged with Sanderson's widow about his approach to the subject, Wells withdrew from the official biography (published in 1923 as "Sanderson of Oundle"; Wells wrote much of the text but the volume was published without listing an author) and published his own work separately.
Saint Bertha of Bingen (German: "Heilige Berta", died ca. 757) was the mother of Rupert of Bingen.
 Her biography was written, and subsequently her cult popularized, by Hildegard of Bingen, who lived in the same region, about three hundred years later.
 Bertha and Rupert share a feast day on May 15.
Hildegard of Bingen, O.S.B. (German: "Hildegard von Bingen" ; ; 1098 – 17 September 1179), also known as Saint Hildegard and Sibyl of the Rhine, was a German Benedictine abbess, writer, composer, philosopher, Christian mystic, visionary, and polymath.
 She is considered to be the founder of scientific natural history in Germany.
Clementia Killewald OSB (born Elisabeth Killewald, 25 April 1954 – 2 July 2016) was a German Benedictine nun, at Eibingen Abbey: serving first as an organist, then by taking care of the elderly and sick, and finally from 2000 as the abbess.
 She introduced the life and work of Hildegard of Bingen, the convent's founder, during the 2012 ceremony when Pope Benedict XVI proclaimed Hildegard a Saint and a Doctor of the Church.
Eijun Linda Cutts (born 1947) is a Sōtō Zen priest practicing in the lineage of Shunryu Suzuki, a Senior Dharma Teacher at the San Francisco Zen Center.
 Cutts is a Dharma heir of Tenshin Reb Anderson, having received Dharma transmission from him in 1996.
 She served as co-abbess of the San Francisco Zen Center from 2000 to 2007, and had first begun practice at the San Francisco Zen Center in 1971; later, she was ordained a priest by Zentatsu Richard Baker in 1975.
 Currently living at Green Gulch Farm Zen Center, as abbess she had been aware of the significance in being a woman in a leadership position in religion that has historically been a patriarchy.
 In this vein, within her first year as abbess she instituted the ceremony in which female ancestors could be honored.
 She became Central Abbess of San Francisco Zen Center in 2014.
Bertha Vyver (11 June 1854 – 20 November 1941) was a caretaker for Scottish poet Charles Mackay and the companion of Marie Corelli.
 From 1875 until his death in 1889, Vyver kept house and nursed Mackay, later caring for her own mother prior to her death.
 Relieved of her nursing duties, Vyver remained with Corelli encouraging and facilitating her writing career.
 When Corelli died, Vyver became executor of her literary estate and wrote a biography of the author.
Kitty Brazelton (born 1951 in Cambridge, Massachusetts) is an American vocalist, composer, flutist, lead singer, and bandleader.
 Her bands include progressive rock/folk rock/contemporary classical "Musica Orbis", metal "V", power pop "Hide the Babies", the art rock/alternative rock/avant-garde jazz band "Dadadah", punk rock/computer music trio "What Is It Like To Be A Bat?"
 and "Hildegurls" (with Eve Beglarian, Lisa Bielawa and Elaine Kaplinsky) who appeared at Lincoln Center for the Performing Arts Festival '98 in celebration of abbess composer Hildegard von Bingen's 900th birthday.
 Brazelton is the daughter of pediatrician and author T. Berry Brazelton.
Deborah Baker is a biographer and essayist.
 She is married to the writer Amitav Ghosh and lives in Brooklyn, Calcutta, and Goa.
 She is the author of "A Blue Hand: The Beats in India", a biography of Allen Ginsberg that focuses on his time in India and of "In Extremis: The Life of Laura Riding", a finalist for the Pulitzer Prize in biography in 1994.
 She also writes for the "Los Angeles Times".
 Her book "The Convert: A Tale of Exile and Extremism" (2011) is a biography of Maryam Jameelah (born Margaret Marcus), a Jewish woman from New York who converted to Islam.
 In 2012, she wrote a critical review for the "Wall Street Journal" of "Defender of the Realm", the Manchester-Reid biography of Winston Churchill.
Beverly Mayne Kienzle (born 1947) retired in 2015 as the John H. Morison Professor of the Practice in Latin and Romance Languages at the Harvard Divinity School, Harvard University.
 She is a specialist in Christian Latin, Latin paleography, and medieval Christianity.
 She has published over seventy articles and fifteen books, including five on Hildegard of Bingen.
 Her latest book is an authoritative biography of her grandmother, Virginia Cary Hudson, author of the best-selling "O Ye Jigs and Juleps!"
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Disibodenberg is a monastery ruin in Rhineland-Palatinate, Germany.
 It was founded by Saint Disibod.
 Hildegard of Bingen, who wrote Disibod's biography "Vita Sancti Disibodi", lived in Disibodenberg for 39 years.