Background
After 20th-century civilization was destroyed by a global nuclear war, known as the "Flame Deluge", there was a violent backlash against the culture of advanced knowledge and technology that had led to the development of nuclear weapons. During this backlash, called the "Simplification", anyone of learning, and eventually anyone who could even read, was likely to be killed by rampaging mobs, who proudly took on the name of "Simpletons". Illiteracy became almost universal, and books were destroyed en masse.
Isaac Edward Leibowitz, a Jewish electrical engineer working for the United States military, survived the war and sought refuge from the mobs of the "Simplification" in the sanctuary of a Cistercian monastery, all the while surreptitiously searching for his wife, from whom he had become separated in the war. Eventually concluding that his wife was dead, he joined the monastery, took holy orders (becoming a priest), and dedicated his life to preserving knowledge by hiding books, smuggling them to safety (known as "booklegging"), memorizing, and copying them. He approached the Church for permission to found a new monastic order dedicated to this purpose. With permission granted, he founded his new order in the desert of the American Southwest, where it became known as the "Albertian Order of Leibowitz". The Order's abbey is located in a remote desert in New Mexico, possibly near the military base where Leibowitz worked before the war, on an old road that may have been "a portion of the shortest route from the Great Salt Lake to Old El Paso". Leibowitz was eventually betrayed and martyred. Later beatified by the Roman Catholic Church, he became a candidate for sainthood.
Six hundred years after his death, the abbey still preserves the "Memorabilia", the collected writings and artifacts of 20th-century civilization that survived the Flame Deluge and the Simplification, in the hope that they will help future generations reclaim forgotten science.
The story is structured in three parts: "Fiat Homo", "Fiat Lux", and "Fiat Voluntas Tua". The parts are separated by periods of six centuries each.
Fiat Homo ("Let There Be Man")
In the 26th century, a 17-year-old novice named Brother Francis Gerard of Utah is on a vigil in a New Mexico desert. While searching for a rock to complete a shelter from the desert wolves, Brother Francis encounters a vagrant Wanderer, apparently looking for the abbey, who inscribes Hebrew on a rock that appears to be the perfect fit for the shelter. When Brother Francis picks up the rock, he discovers the entrance to an ancient fallout shelter[a] containing "relics", such as handwritten notes on crumbling memo pads bearing cryptic texts resembling a 20th-century shopping list.[b] He soon realizes that these notes appear to have been written by Leibowitz, his order's founder. The discovery of the ancient documents causes an uproar at the monastery, as the other monks speculate that the relics once belonged to Leibowitz. Brother Francis's account of the Wanderer, who ultimately never turned up at the abbey, is also greatly embellished by the other monks amid rumours that he was an apparition of Leibowitz himself; Francis strenuously denies the embellishments, but equally persistently refuses to deny that the encounter occurred, despite the lack of other witnesses. Abbot Arkos, the head of the monastery, worries that the discovery of so many potentially holy relics in such a short period may cause delays in Leibowitz's canonization process. Francis is banished back to the desert to complete his vigil and defuse the sensationalism.
Many years later, the abbey is visited by Monsignors Aguerra (God's Advocate) and Flaught (the Devil's Advocate), the Church's investigators in the case for Leibowitz's sainthood. Leibowitz is eventually canonized as Saint Leibowitz – based partly on the evidence Francis discovered in the shelter – and Brother Francis is sent to New Rome to represent the Order at the canonization Mass. He brings with him the documents found in the shelter, and an illumination of one of the documents on which he has spent years working, as a gift to the Pope.
En route, he is robbed by "The Pope's Children" – an ironic name for outcast genetic mutants who are the descendants of fallout victims – and his illumination is taken, though he negotiates with the robbers to keep the original blueprint on which the illuminated copy was based. The robbers believe the gold-inlaid copy is the original and the blueprint the worthless copy. Francis completes the journey to New Rome and is granted an audience with the Pope.[c] Francis presents the Pope with the remaining blueprint, and the Pope comforts Francis with the notion that the fifteen years he spent creating the illumination were not rendered a waste by the theft, but rather were essential in protecting the original relic. The Pope also aids Francis by giving him gold with which to ransom back the illumination; however, Francis is killed during his return trip by the Pope's Children, receiving an arrow between the eyes, just after he spots the approach of the Wanderer in the distance. The Wanderer discovers and buries Francis's body. The narrative then focuses on the buzzards who were denied their meal by the burial; they fly over the Great Plains and find much food near the Red River until a city-state, based in Texarkana, rises.
Fiat Lux ("Let There Be Light")
North America in 3174, showing Texark territory in yellow. The Texark expansion as described in this story and in Saint Leibowitz and the Wild Horse Woman is marked in orange.In 3174, the Albertian Order of Saint Leibowitz is still preserving the half-understood knowledge from before the Flame Deluge and the subsequent Age of Simplification. The new Dark Age is ending, however, and a new Renaissance is beginning. Thon Taddeo Pfardentrott, a highly regarded secular scholar, is sent by his cousin Hannegan, Mayor of Texarkana, to the abbey. Thon Taddeo, frequently compared to Galileo, is interested in the Order's preserved collection of Memorabilia.
At the abbey, Brother Kornhoer, a talented engineer, has just finished work on a "generator of electrical essences", a treadmill-powered electrical generator that powers an arc lamp. He gives credit for the generator to work done by Thon Taddeo. Arriving at the monastery, Thon Taddeo immediately recognizes the significance of Brother Kornhoer's pioneering work. By studying the Memorabilia, Thon Taddeo makes several major "discoveries", and asks the abbot to allow the Memorabilia to be removed to Texarkana. The Abbot Dom Paulo refuses, offering to allow Thon Taddeo to continue his research at the abbey instead. Before departing, the Thon comments that it could take decades to finish analyzing the Memorabilia.
The Wanderer, now called Benjamin, has settled down as a hermit within sight of the abbey, and has struck up a relationship with the abbot. Before Thon Taddeo departs, Benjamin visits the abbey to meet the Thon, to see if he is the long-awaited Messiah.
Meanwhile, Hannegan makes an alliance with the kingdom of Laredo and the neighboring, relatively civilized city-states against the threat of attack from nomadic warriors living on the plains. Hannegan, however, is secretly manipulating the regional politics to effectively neutralize all of his enemies, leaving him in control of the entire region. Monsignor Apollo, the papal nuncio to Hannegan's court, sends word to New Rome that Hannegan intends to attack the Empire of Denver next, and that he intends to use the abbey as a base of operations from which to conduct the campaign. For his actions, Apollo is executed, and Hannegan initiates a church schism, declaring loyalty to the Pope to be punishable by death. The Church excommunicates Hannegan.
Fiat Voluntas Tua ("Thy Will Be Done")
In the year 3781, mankind has emerged into a new technological age, and now possesses nuclear energy and weapons again, as well as starships and extrasolar colonies. Two world superpowers, the Asian Coalition and the Atlantic Confederacy, have been embroiled in a cold war for 50 years. The Leibowitzian Order's mission of preserving the Memorabilia has expanded to the preservation of all knowledge.
Rumors that both sides are assembling nuclear weapons in space, and that a nuclear weapon has been detonated, increase public and international tensions. At the abbey, the current abbot, Dom Jethras Zerchi, recommends to New Rome that the Church reactivate the Quo peregrinatur grex pastor secum ("Whither wanders the flock, the shepherd is with them"), a contingency plan in the case of another global apocalypse which involves "certain (spacefaring) vehicles" the Church has had since 3756. A "nuclear incident" occurs in the Asian Coalition city of Itu Wan: an underground nuclear explosion has destroyed the city, and the Atlantic Confederacy counters by firing a "warning shot" over the South Pacific. Rumors swirl about whether the city's devastation was deliberate or accidental.
New Rome tells Zerchi to proceed with Quo peregrinatur, and to plan for departure within three days. He appoints Brother Joshua as mission leader, telling him that the mission is an emergency plan for perpetuating the Church on extrasolar colony planets in the event of a nuclear war on Earth. The Order's Memorabilia will also accompany the mission. That night the Atlantic Confederacy launches an assault against Asian Coalition space platforms. The Asian Coalition responds by using a nuclear weapon against the Confederacy capital city of Texarkana, which kills millions of people. A ten-day cease-fire is issued by the World Court. The Wanderer reappears at the rectory, at the last meal before Brother Joshua and the space-trained monks and priests depart on a secret chartered flight for New Rome, hoping to leave Earth on the starship before the cease-fire ends.
During the cease-fire, the abbey offers shelter to refugees fleeing the regions affected by fallout, which results in a battle of wills over the euthanasia of hopelessly irradiated refugees between the abbot and a doctor from a government emergency response camp. The war resumes, and a nuclear explosion occurs near the abbey. Abbot Zerchi tries to flee to safety, bringing with him the abbey's ciborium containing consecrated hosts, but it is too late. He is trapped by the falling walls of the abbey and finds himself lying under tons of rock and bones as the abbey's ancient crypts disgorge their contents. Among them is a skull with an arrow hole in its forehead (presumably that of Brother Francis Gerard from the first section of the book).
As he lies dying under the abbey's rubble, Zerchi is startled to encounter Mrs. Grales/Rachel, a tomato peddler and two-headed mutant. However, Mrs. Grales has been rendered unconscious by the explosion, and appears to be dying herself. As Zerchi tries to conditionally baptize Rachel, she refuses, and instead takes the ciborium and administers the Eucharist to him. It is implied that she is, like the Virgin Mary, exempt from original sin. Zerchi soon dies, having witnessed an apparent miracle.
After the abbot's death, the scene briefly flashes to Joshua and the Quo peregrinatur crew, who are preparing to launch as the nuclear explosions begin. Joshua, the last crew member to board the starship, knocks the dirt from his sandals (a reference to Matthew 10:14, "If anyone will not welcome you or listen to your words, leave that home or town and shake the dust off your feet"), murmuring "Sic transit mundus" ("Thus passes the world", a play on the phrase sic transit gloria mundi, "thus passes the glory of the world").
As a coda, a final vignette depicts the ecological aspects of the war: seabirds and fish succumb to the poisonous fallout, and a shark evades death only by moving to particularly deep water, where, it is noted, the shark was "very hungry that season".
