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Literature / A Canticle for Leibowitz

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A Canticle for Leibowitz is a post-apocalyptic science fiction novel by American Walter M. Miller, Jr., first published in 1960. It's based on three short stories Miller contributed to the science fiction magazine The Magazine of Fantasy and Science Fiction; it is the only novel published by the author during his lifetime. Considered one of the classics of science fiction, it has never been out of print and has seen over 25 reprints and editions. Appealing to mainstream and genre critics and readers alike, it won the 1961 Hugo Award for best science fiction novel. It heavily influenced the Fallout series of games.

Set in a Roman Catholic monastery in the desert of the Southwestern United States after a devastating nuclear war, the story spans thousands of years as civilization rebuilds itself. The monks of the Albertian Order of Leibowitz take up the mission of preserving the surviving remnants of man's scientific knowledge until the day the outside world is again ready for it. The novel has three parts in different time periods and shows how the monastery and the world change over time.


Inspired by the author's participation in the Allied bombing of the monastery at Monte Cassino during World War II, the novel is considered a masterpiece by literary critics. It has been compared favorably with the works of Evelyn Waugh, Graham Greene, and Walker Percy, and its themes of religion, recurrence, and church versus state have generated a significant body of scholarly research. Miller's follow-up work, Saint Leibowitz And The Wild Horse Woman, was published posthumously in 1997.


Tropes in the book include:

  • Aerith and Bob: While a number of common religious names like Rachel and Francis persist throughout the centuries, the names of non-religious folk gradually get stranger over the centuries, thanks to changes in language and culture. So you get a character named Joshua acting as a contemporary to men named Taddeo and Kornhoer.
  • After the End: The story is set after a nuclear holocaust destroys modern civilization, following the history of post-apolcapypse North America from the early, chaotic period as civilization struggled to reestablish itself all the way up to the second end.
  • Age Without Youth: The recurring Jew appears to grow older but never dies even as the book jumps centuries into the future, a fact which perplexes the other characters.
  • All Hail the Great God Mickey!: The first chapter is set in the 26th century, long after a disastrous nuclear war. A seventeen-year-old novice named Brother Francis Gerard is on a vigil in the desert. While searching for a rock to complete a shelter, he encounters a pilgrim who inscribes Hebrew on a rock that appears the perfect fit for the shelter. When Brother Francis removes the rock he discovers the entrance to an ancient fallout shelter containing "relics", such as handwritten notes on crumbling memo pads bearing cryptic texts resembling a 20th-century shopping list. He soon realizes that these notes appear to have been written by Leibowitz, the founder of his order. The discovery of the ancient documents causes an uproar at the monastery, as the other monks speculate that the relics once belonged to Leibowitz. The items are then used as evidence in Leibowitz's canonization process, thus making them actual holy relics under the Church's definition.
  • Alternate History: A honorary one at least. The Deluge was said to have taken place around the late 1960s, with hints of somewhat more advanced technology than the real one. It can also be presumed that Vatican II was never issued in that timeline.
  • Ambiguously Jewish: It's never outright stated that Isaac Leibowitz was Jewish, though it's heavily implied by his name and his similarity to Jewish physicists like Albert Einstein and Robert Oppenheimer.
  • And Man Grew Proud: A common theme is that as society develops high technology and becomes able to build weapons of fantastic power, it loses touch with its spiritual and ethical side.
  • Anti-Intellectualism: Simplification turned it to radical extreme, ending with hunting down people capable of reading. The fallout of the movement kept humanity on its knees for centuries.
  • Anyone Can Die: And they do by the dozen — almost all named characters die during the story and humanity itself managed to destroy the world for the second time.
  • Apocalypse Anarchy: The chaos in the wake of the Flame Deluge and the Simplification that followed all but guaranteed the near-total collapse of civilization. It would be well over a thousand years before mankind surpasses the pre-Deluge world only to nearly destroy itself again.
  • Apocalypse How: Class 1, edging towards Class 2, the nuclear war being referred to as "The Flame Deluge". The end implies that the result of the second nuclear war was a Class 3... on Earth, anyway.
  • Apocalyptic Log: The papers Brother Francis finds in the fallout shelter detail a man with the initials I.L. attempts to find a plane to bring his wife to their fallout shelter. He suspects this man might his long-dead patron saint, Isaac Leibowitz, which is confirmed when he finds a number of Leibowitz's blueprints for nuclear devices that ended human civilization.
  • Badass Preacher: It's implied the monks, despite being generally non-violent, have defended the abbey with arms multiple times in its history.
  • Barbarian Tribe: These figure most prominently in the tribal peoples plaguing the fledging settlements of Fiat Homo, which are implied to be descended from the old Simpleton mobs. They also show up in the form of the Plains Nomads of Fiat Lux and Saint Leibowitz And The Wild Horsewoman.
  • Bindle Stick: Standard traveler equipment includes a bag on a stick, at least in the first era shown. A monk leaving the monastery always carries a book in it.
  • Bittersweet Ending:
  • Black Comedy: Evident throughout the novel, showing the folly of mankind's existence in contrast to the monks' mission. The Catholic Church itself is also given this treatment in the novel, whether it's the endless theological disputes or the irony of the "Pope's Children". In addition, each part ends with the events being viewed from the perspective of buzzards though the end has them replaced with a lucky shark.
  • Cargo Cult: It's mentioned in Fiat Homo that the more primitive tribals are fond of using relics like broken transistors and radio parts as spiritual items, some occasionally dying from ingesting them. Though even the Catholic Church, via the abbey, indulges in this a bit given how the Memorabilia are treated as nigh sacrosanct.
  • The Catfish: In Fiat Homo, the giant catfish Bo'dollos is rumoured to haunt a lake formed over a crater once occupied by a village and an intercontinental launching pad, complete with "several fascinating subterranean storage tanks". The lake has apparently very good fishing, but the local shepherds avoid it due to their belief that the fish are the souls of the villagers and excavators lost in the lake's creation, and out of fear of Bo'dollos. Incidentally, the site was excavated by a monk known as the Venerable Boedullus.
  • The Chessmaster: Hannegan, who is also quite the Magnificent Bastard. He played everyone and their dog to do exactly what he wanted them to do, leading to his complete hegemony. It's strongly implied the empire he built is one of the two world superpowers from Fiat Voluntas Tua.
  • Church Militant: Abbot Zerchi, which leads him to a Heel Realization after attempting to stop a victim of radiation poisoning and her infant daughter from euthanasia.
  • Continuity Nod: At the very end of the book, The abbot finds the skull of Francis, the protagonist of the first third of the book. It is, of course, symbolic: both men complete their mission and ensure that humanity can grow and flourish once more, but neither survives to witness the consequences.
  • Conveniently Precise Translation: Averted; Francis has quite a bit of difficulty translating the technical jargon he finds in the fallout shelter. Later, a machine translator is invented which (like its Real Life counterparts) is somewhat less than reliable.
  • Court Jester: The Poet fills the role of the Shakespearean fool, as he points out hypocrisies in the form of jokes that go over the heads of the priests and barbarian lords in his company. He's a little to sardonic for his own good, leaving him unemployed and eventually sending him on the run from a barbarian lord who doesn't find the Poet's audition for court jester a little too insulting.
  • Crapsack World: The generations after the Great Deluge are one of brutality, war, and constant hardship even as humanity rediscovers and ultimately surpasses what had been lost. Only to cause a second Great Deluge. That said, many characters choose to interpret it as A World Half Full.
  • Days of Future Past: The cyclical nature of history is a major theme of the book, with "Fiat Homo" modeled after the early Middle Ages, and "Fiat Lux" closely resembling the Renaissance. Likewise, the Texarkana Schism bears more than a passing resemblance to Henry VIII's English Reformation. And that's not counting the Manifest Destiny in St. Leibowitz and the Wild Horse Woman, or the Cold War analogy in "Fiat Voluntas Tua."
  • Deconstruction: Of the idea common in more secularly-oriented science fiction that technological progress necessarily implies social progress. Canticle makes the point that no matter how advanced the technology gets, the human heart is inclined to a certain moral laziness that needs to be carefully and consciously guarded against if people aspire to be anything more than barbarians with fancy toys.
  • Distant Finale: 1,200 years after "Fiat Homo".
  • Divided States of America: By the time of "Fiat Lux", where America used to be consists of several city-state "empires" which don't even speak the same language.
  • Downer Ending: It's very easy to interpret the very bitter note of the Bittersweet Ending as outright downer. Humanity destroyed itself for the second time, learning nothing from the past. The magnitude of the destruction is implied as much more severe than the first time around. But what really seals it is how the monks left the Earth — for good. Whatever and whoever survives, if it's even possible to survive, is left for themselves.
    • The sequel also has a downer ending. The Crusade to bring the Papacy back to New Rome and destroy the Empire of Texark is lost. New Rome is sacked by the Nomad armies brought by the Pope to take back the city. Cardinal (now Pope) Brownpony commits Seppuku in a burned out St. Peter's Cathedral once he realizes the extent of his mistake. The Plains Nomads are turned against each other and are implied to be wiped out in the coming years. Texark moves the Papacy to Hannegan City and completely under its thumb. Its implied that Blacktooth never sees his lover Ædrea again after searching for most of the book, though he seems content with that.
  • Eagleland: The series is set entirely within the American landmass. The papacy has its seat in the vicinity of where St. Louis used to be, and retreats to Denver after the Texarkanan Schism.
  • The Empire: Texarkana, which grows under Hannegan's rule exceptionally. By Fiat Voluntas Tua, it becomes the heart of the Atlantic Confederacy, one of the two superpowers that eventually plunge the world into another nuclear holocaust.
  • Everyone Calls Him "Barkeep": The Poet who lives at the abbey is only referred to by his occupation, or disparagingly as the Poet-sirrah. Even after he becomes a folk saint, he's only ever called Poet.
  • Evil Luddite: The Simplification was the backlash of a group of self-proclaimed "simpletons" against scientists and other intellectuals, whom they blamed for the Flame Deluge. Leibowitz himself was one of their victims. The initial movement quickly get out of hand and turned into a very literal witch hunt. First the politicians, then scientists, teachers, students, and finally people who can read.
  • Fallout Shelter Fail: In Fiat Homo, the monks and Church scholars piece enough together from the shelter Francis finds to conclude that a cave-in of some sort occurred at the entrance around the time of the Flame Deluge. Not only killing Leibowitz's wife in the process, but also trapping the unlucky denizens inside as they suffocate to death, as the main door didn't swing inward.
  • Fantastic Catholicism: Due to internal organization and bit of luck, Catholic Church was one of the few, if not the only institution to survive Flame Deluge and definitely the only one to thrive. The story almost entirely focuses on the monastery started by Leibowitz, preserving as much knowledge of the old world as possible.
  • Fantastic Religious Weirdness: The story essentially chronicles how the Catholic Church manages to survive (and, in so doing, help ensure the survival of humanity) after an apocalyptic nuclear war knocks human progress back a thousand years or so. Some issues, such as whether or not mutants have proper souls and thus can be regarded as fully human, are mentioned in passing. There's a hysterical (if you're Catholic) couple of paragraphs on the reason the Vatican hasn't gotten around to canonizing Blessed Leibowitz yet: they're stuck in seemingly endless debate on the details of the "Preternatural Gifts of the Virgin Mary."note 
  • Fantasy Counterpart Culture: As noted, post-apocalyptic America is essentially medieval Europe, with a Dark Age, a Renaissance and modernity, and the appropriate conflicts between science and faith. By the end of the book, the two poles of the international system are loosely based on the Cold War. And then the Flame Deluge repeats — with one key difference.
  • Feudal Future: Justified, seeing that an Age of Simplification leads to a new dark age.
  • Fling a Light into the Future:
    • After the Flame Deluge, the entire purpose of the monks' work is to preserve a fragment of human knowledge for future generations who will be able to understand it better.
    • After civilization rises again, and falls again, the church survives by sending off a mission ship to one of the offworld colonies.
  • Flying Dutchman: The Wandering Jew. Maybe.
  • Future Imperfect: So much, both Justified and Played for Laughs:
    • The Simplification was so total in grinding down civilization that by Fiat Homo, most of what's known about the past is through folklore and distorted accounts. That said, the abbey, and to a lesser extent the Catholic Church at large, have preserved as much pre-Deluge knowledge as they could, though even they have at best a fragmented portrait of what happened.
    • When Brother Francis finds the fallout shelter at the beginning of the book, he thinks it was meant as a prison to hold a terrible monster called a Fallout, as by that point no-one remembered what nuclear fallout actually was, and folklore had given the name to a race of terrible demons born from the Flame Deluge.
    • In order to copy a blueprint, Francis covers the entire page with blue ink to "outline" the diagram instead of drawing it, thinking that if that's the way the advanced civilization wanted to display the diagram there probably was some significance to it. He only finds out later that the color is the result of carbon copy paper, and laments how much ink he wasted.
    • One of the monks in "Fiat Lux" suggests that the Pre-Deluge Church may have used arc lamps on their altars instead of candles. The Abbot is not pleased.
    • Brother Francis plays an important role in getting Leibowitz canonized. Centuries later, one monk doesn't even remember who he is.
    • Thon Taddeo is described as a brilliant genius comparable to Albert Einstein. But by the time of Fiat Voluntas Tua, even the monks have trouble recalling his name.
    • The circumstances behind the Flame Deluge and its immediate aftermath, such as who the U.S. President was at the time or who fired first, are hotly contested. Yet every monk seems to take for granted that Leibowitz's wife had a gold tooth.
    • The narration regarding the Simpletons and the last days of the pre-Deluge world reads like a liturgical sermon that would be more fitting for Martin Luther's time than Martin Luther King Jr.'s;
      Let us stone and disembowel and burn the ones who did this thing. Let us make a holocaust of those who wrought this crime, together with their hirelings and their wise men; burning, let them perish, and all their works, their names, and even their memories. Let us destroy them all, and teach our children that the world is new, that they may know nothing of the deeds that went before. Let us make a great simplification, and then the world shall begin again.
    • Hilariously enough, the Simpletons' rallying cry, which managed to survive intact down the generations, sounds much more like what working-class Americans would say.
      Simpletons! Yes, yes! I'm a simpleton! Are you a simpleton? We'll build a town and we'll name it Simple Town, because by then all the smart bastards that caused all this, they'll be dead! Simpletons! Let's go! This ought to show 'em! Anybody here not a simpleton? Get the bastard, if there is!
    • A monk mentions the Theory of Evolution has been developed as a possibility, and is scoffed at by the secular Thon Thaddeo.
    • As of "Fiat Voluntas Tua", the Poet-sirrah of "Fiat Lux" has become a folk hero, but "official" history considers him a legend rather than someone who actually existed.
    • Also in "Fiat Voluntas Tua", the identities of the two characters in an ancient satirical dialogue are lost to history. It is strongly implied that the characters, "The Poet" and "The Thon", are caricatures of the Poet-sirrah and Thon Thaddeo, and that the dialogue has been written shortly after the events "Fiat Lux".
  • The Gadfly: The Poet in Fiat Lux. He manages to get a number of unpleasant topics out in the open that would be difficult for the monks to broach on their own.
  • Gadgeteer Genius: Brother Kornhoer, who builds the first working electrical generator solely by following textbooks explaining electricity and theoretical power-generation. He even notes the only reason he stopped at arc lamp rather than proper light bulb was lack of proper materials.
  • Gainax Ending: The Second Coming of Christ (or the return of the Virgin Mary) is a tomato saleswoman's green-eyed radiation-eating conjoined fetus head, at least if the priest thinking this hasn't just gone insane.
  • Gratuitous Latin: As the lingua franca of the Church, Latin is used all over the place in the books, sometimes translated, sometimes not.
  • Fictional Counterpart: The Green Star is very clearly a counterpart to The Red Cross, since they're both international, non-profits dedicated to medical care named after a simple symbol in a specific color.
  • Hate Sink: How to justify Poet killing a man in cold blood? Well of course, let said man order a slaughter of unarmed civilians, while getting his own hands dirty!
  • Here We Go Again! / History Repeats / Eternal Recurrence : One of the main themes of the novel is the cyclical nature of human history.
  • The Hermit: The Old Jew Benjamin.
  • Heroic Resolve: Poet is surprised by his own sudden surge of heroism, when he attacks Texarkanan officer, who was busy killing scared civilians. This ends with Mutual Kill, while Poet notes the irony of getting involved into conflict that doesn't bother him in the slightest.
  • Hollywood Apocrypha: The account of the Flame Deluge recounted in "Fiat Lux", which is explicitly stated to have been written by someone with a penchant for Scriptural mimicry. The beginning of the story borrows language from the Book of Job and the Flood narrative in Genesis; the conversation between God and the leader after the nuclear war is reminiscent of God's conversation with Cain after Abel's murder.
  • Homeworld Evacuation: The book ends with the Church leaving Earth to escape the nuclear holocaust.
  • Hope Spot: The Quo Peregrinatur starship. It leaves the Earth before things go FUBAR.
  • Idiot Hero: Brother Francis Gerard, who is quite the Wide-Eyed Idealist. It eventually gets him killed.
  • I'm a Humanitarian: Some of the mutants practice cannibalism even long after the basic shortage of food ceased to be a factor.
  • In Your Nature to Destroy Yourselves: Why humanity develops nuclear weapons and destroys civilization a second time.
  • Inadequate Inheritor:
    • In Fiat Lux, Thon Taddeo comes to see himself as this the more he delves into the Memorabilia, realizing that for all his genius, he's only rediscovering the accomplishments of the past. Though he's standing on the shoulders of giants, he doesn't take it too well.
    • By Fiat Voluntas Tua, Abbot Zerchi and by extension, the Catholic Church, ultimately come to the conclusion that humanity itself is this, having failed to truly learn from the Great Deluge and in the process, sparked another one. The Church instead has the Memorabilia taken to the off-world colonies with a group of clergy and children in the hopes that they would fare better.
  • Insufferable Genius: Justified with Thon Taddeo. He feels miserable himself, because in all his brilliance, he is merely rediscovering things obvious to the "ancients". A brief visit in the monastery to read part of the collected books sends him on a brink of depression how all his contemporary "genius" is a common knowledge from the past. This makes him feel insecure and actively lash against people questioning his authority.
  • Insult Backfire: The "Simplification" didn't really swing into high gear until some of the last scholars called the rampaging mobs "bloodthirsty simpletons."
  • Ironic Echo: The monks eventually come to believe that mankind is seeking to recreate the Garden of Eden through secular means. Yet just as humanity was cast from the Biblical Paradise and barred from entering it, so too would they fail in that quest and be denied it through another Flame Deluge.
  • Istanbul (Not Constantinople): Texark and the Misery (Missouri) River.
    • The town near the abbey has its name corrupted to "Sanly Bowitts".
    • The city known today as Amarillo (Texas) is shown on maps in the sequel as "Yellow". ("Amarillo" is Spanish for "yellow".)
  • Jumping Off the Slippery Slope: The Simplification in a nutshell, which quickly lost any sense of control or order. What began as an anti-intellectualism movement against the surviving politicians and scientists for the nuclear war devolved into mobs lynching people able to read, thus becoming the final nail in civilization's coffin.
  • Just Before the End: The third part of the book starts after the initial, limited exchange of warheads already happened. It goes only worse from there.
  • Justified Title: Lebowitz is canonized over the course of the course of the work, so it makes sense. As a bit of a Genius Bonus, it's designed to grab the prospective reader's attention be wondering why a Canticle (A Christian song) is being sung for Leibowitz (A commonly Jewish last name).
  • Kill Sat: The Asian space platforms that destroy Texarkana and the abbey in the end.
  • Knight Templar: All three of the abbots, each in his own way.
  • Language Drift: "Modern" English is very much a dead language in the future, and must be studied like one. Much like Latin after the fall of the Roman Empire, different dialects of English grew and evolved into full-blown, mutually unintelligible languages like "Alleghenian" and "Southwest."
  • Literal Metaphor: The Old Jew in Dom Paulo's time claims to be several thousand years old, but it's established that as the Diaspora is more thinly scattered than ever, he may be the only Jew for hundreds if not thousands of miles. Thus, he copes with his isolation by seeing himself as the embodiment of all Jewish history. Whether he is also the immortal Wandering Jew is ambiguous.
  • Literary Allusion Title: The book's three parts are titled "Fiat Homo"note  and "Fiat Lux"note , which both come from the Creation account in Genesis, and "Fiat Voluntas Tua"note , which is a line in the Lord's Prayer from The Four Gospels.
  • Loophole Abuse: In Fiat Voluntas Tua, it's revealed that there are international treaties forbidding the production of nuclear weapons. Said laws, however, don't mention such limits in space, resulting in another arms race.
  • Lost Technology: Electricity and computers are unknown to the monks. Humanity at large does figure out how to build them for themselves later in the story. At which point the monks' goal has shifted from protecting the Memorabilia to protecting all knowledge.
    • On a lesser note, concrete gets forgotten. Brother Francis talks about the ancient stones with metal rods inside of it as something almost mystical. It's also implied the first monastery was build at least partially from concrete rubble.
    • Somewhere between the time directly after the Flame Deluge and Fiat Homo, the information about blueprints being blue and white because they are a negative of the original plans was forgotten or lost. Cue monks spending weeks on carefully covering entire pages in rare blue ink by hand, dead-sure it's the way how it's supposed to be done.
    • Notably averted with printing press and movable type. One of the abbots before Fiat Homo quickly realised printing press only makes sense if they are going to mass-produce those books. Otherwise it will simply take more time and effort to print them in few copies than to hand-write them. Eventually the press is used when there is demand for the books stored in the abbey.
  • Magical Jew: Benjamin, a quirky but wise Jewish Hermit Guru who may or may not be the Wandering Jew.
  • Maybe Magic, Maybe Mundane:
    • Benjamin may feature as the immortal Wandering Jew. Or maybe not. The story is vague about whether or not the whole thing is Zerchi's Dying Dream.
    • The fate of Rachel and the strangeness of the Poet and also count.
  • Meaningful Name:
    • Many of the place names in the stories vaguely refer to places that readers might know; some, like Denver and Chihuahua, survive remarkably intact.
    • The Memorabilia that Leibowitz first started and continued by the abbey's monks over the centuries is for all intents and purposes the collected memory of the old world.
  • Mercy Kill: What the medics authorize for radiation victims. The monks, especially Abbot Zerchi, protest against them vociferously with signs.
    • Poet performs one on the officer he wounded himself.
  • Mutants: After the Flame Deluge, mutations became common among humanity as a result of the high radiation levels. The mutants are described as coming in many different flavors, from simply having patches of skin in various shades to a full-on Multiple Head Case. They are known as "the Pope's Children" after the Pope issues an edict that they are not to be harmed. Unfortunately for Brother Francis, they didn't return the favor. Other times, the are called "the children of the Fallout" for rather obvious reasons.
  • Mysterious Watcher: The Old Jew, who lives on a mesa and watches over the abbey.
  • No OSHA Compliance: One of the monks ends up blinded, because he was manually operating an arc lamp without proper eye protection. Nobody even knew how damaging it will be for his eyes, so he ended up operating the lamp for few days.
  • Nuclear Weapons Taboo: Ultimately averted. Despite post-apocalyptic folklore and Church teaching both blaming nuclear war for the Flame Deluge, however ill-understood, they don't prevent the creation of even more powerful nukes by the superpowers around the time of Fiat Voluntas Tua. And just as before, they fail to prevent another atomic holocaust.
  • Outgrown Such Silly Superstitions: What the secularists want to believe, despite consistent evidence that the monks are actually closer-to-earth.
    • Curiously, it's implied that in general, people were no more religious than they were before the Deluge.
    • It's even lampshaded during the debate between Dom Paulo and Thon Taddeo, with the former rebuking the notion that the past was really as "enlightened" as the latter believes.
      “It never was any better, it never will be any better. It will only be richer or poorer, sadder but not wiser, until the very last day.”
  • Patchwork Story: The book started out as three short stories, "A Canticle for Leibowitz", "And the Light Is Risen", and "The Last Canticle".
  • Patron Saint: The monastery's founder, St. Leibowitz, becomes the patron saint of electricians once the world has them again. There is also a reference to Saint Raul the Cyclopean, patron of the misborn.
  • Persecuted Intellectuals: Part of the aftermath of global nuclear war. After the enraged survivors slaughter the scientists who developed the bombs, they begin to target other scientists... and then other scholars... and then anyone with a formal education... and finally, anyone who could read. The result is a society of "simpletons" where admitting that you know anything can get you burned at the stake.
  • Posthumous Character: Saint Leibowitz, though just how posthumous he really is is up for debate.
  • Pre-Mortem One-Liner: When a dying bandit starts deliriously spouting off a last confession, the Poet says "Ego te absolvo, son" and stabs him in the neck mid-sentence.
  • Proud Warrior Race Guy: The nomadic chief. Which makes him all that easier to exploit and use by Hannegan.
  • Ragnarök Proofing: Bits and pieces of the pre-Deluge world become increasingly rare as time passes. By the time Fiat Homo takes place, many topside ruins had already been picked clean by scavengers over the generations, leaving only hollow shells with only traces of what they once had been. It's mentioned, however, that at some point group of monks stumbled on a relatively intact nuclear missile facility hidden beneath a village which they accidentally detonate.
  • Reasonable Authority Figure: Pope Leo XXI.
  • The Remnant: The Catholic Church is a surviving constant from the pre-Deluge world. By Fiat Lux it's the only institution from the old world still around.
  • Ruins of the Modern Age: Largely averted. In Fiat Homo, most surface ruins had long been scavenged of anything valuable to the point that they're barely recognizable as such. By Fiat Lux, they're all but absent.
  • Saintly Church: The Catholic Church is portrayed both realistically and sympathetically.
    • Subverted in the sequel, where the church is portrayed both pragmatically and very cynically. Miller was thoroughly disillusioned with the Church in his old age.
  • Scavenger World: At least initially.
    • Fiat Homo takes place six centuries after the Flame Deluge and there is barely anything left to scavenge at this point. Many ruins had already been picked clean, though it's mentioned that rusted transitors still wind up in the hands of tribal chieftains.
    • In Fiat Lux, when asked by Thon Taddeo on what became of the great weapons and machines used by pre-Deluge humanity, Monsignor Apollo simply says that they were made into "plowshares and hoes."
  • Science Is Bad:
    • Subverted, if not outright defied. One of the chief conflicts of the story is how to use the knowledge gained from civilization's renaissance properly. Science and knowledge in general in itself is not bad, but people's applications of it can be.
    • In-universe, it's this sort of attitude that led to the Simplification immediately after the Flame Deluge. People blamed the scientists and intellectuals for the war and started lynching them en masse.
  • Science Hero:
    • Leibowitz himself. He was some humble engineer, who eventually died for the cause of preserving human knowledge for the future generations.
    • Thon Taddeo serves as a deconstruction, showing how pursuit for knowledge without any sort of moral guidance can cause more harm and damage than it's worth.
  • Shout-Out: One of the documents Thon Taddeo finds at the abbey is strongly implied to be Rostrum's Universal Robots.
  • The Spymaster: The Vatican Diplomatic Service has gained notoriety, to say the least.
  • Standard Sci-Fi History: Subverted. Although humanity does recover from World War III and rebuilds civilization, history ends up repeating itself. This differentiates the book from other works at the time, which tended to treat history as linear instead of cyclical.
  • Stealth Insult: Early in Fiat Lux, Thon Taddeo dismissively asks Monsignor Apollo, Texarkana's Nuncio to New Rome, after seeing a group of peasants how their forefathers could have fallen so far from the heights prior to the Deluge. The Monsignor, however, responds to his questions with subtle jabs and retorts that reveal the scholar's true colors.
    "How can a great and wise civilization have destroyed itself so completely?"

    "Perhaps," said Apollo, "by being materially great and materially wise, and nothing else."
  • Testosterone Poisoning: In-universe. Members of the nomad tribe Hannegan allied with drink (animal) blood, considering water a "women drink". This makes the younger of the two emissaries send to make the pact quite uneasy.
  • Time Skip: "Fiat Lux" takes place roughly 600 years after "Fiat Homo". "Fiat Voluntas Tua" in turn takes place 607 years after "Fiat Lux".
  • Torches and Pitchforks: The Simplification, where most technology and knowledge was actively destroyed in a backlash against technology after the nuclear war. Which in turn made any organized recovery from the Flame Deluge impossible and send humanity back to pre-medieval stage.
  • Translation Convention: The language the characters speak is not actually English, but a distant descendant of it which is translated for the reader.
  • Translator Microbes: A large device in Abbot Zirchi's office is theoretically able to translate any language it records into another. It kind-of works, but the thing is so complex and old that no capable engineer is willing to mess with it for fear of ruining it further.
  • Translation Train Wreck: The Abominable Autoscribe is a janky piece of technology capable of translating any language it hears into the text of another language, except that it translates the words backwards. So, the word "urgent" into another language as that language's equivalent of "tnergu." This is after the Abbot spent a good part of the day fiddling with each and every one of the computer's hundreds of mechanisms, so without that maintenance, it would probably be even more inaccurate.
  • Walking the Earth: The Old Jew takes to wandering at times.
  • What Happened to the Mouse?: The fate of Benjamin (and his true nature) is left unclear, as is that of Rachel.
  • Wide-Eyed Idealist: Brother Francis is honest, sincere, and hopeful, though he does take the basic honesty and decency of others for granted. This latter fact ultimately gets him killed on his trip back from New Rome.
  • Zeerust: The "Fiat Voluntas Tua" segment has plenty. For instance, Dom Zerchi has a computer with speech-to-text function and a universal translator, but which takes up most of a wall.