First published in 1988 by Isaac Asimov, this prequel is set decades before the events of The Foundation Trilogy, featuring Hari Seldon as the main character. These events are known as "The Flight" In-Universe, and Seldon is convinced to begin seeking a way to predict the future with psychohistory, despite his belief that it cannot be made to work.
The details present in the 1020 F.E. edition of the Encyclopedia Galactica have an incomplete record of these events, providing a contrast to the "real story" of how Seldon attempted to avoid capture at the hands of Emperor Cleon I, and his Chief of Staff, Eto Demerzel. Seldon has recently participated in a mathematics convention, where he described "psychohistory", as a set of maths that might, under extremely limited conditions be possibly able to maybe predict probabilities in a constrained environment. The emperor and Demerzel realize that Seldon could very easily be used, and if he won't be used by them, they plan to prevent him from being used by anyone else.
Seldon encounters Chetter Hummin, who encourages his escape and helps provide locations of safety and forewarning of Demerzel's lackeys. He hides Seldon in Streeling University, where he meets Dors Venabili. Then they escape to the Mycogen sector, where they believe themselves to be the descendants of Aurora. Seldon angers the leadership of Mycogen, and they escape again, this time to the Dahl sector, where they meet Yugo Amaryl and Raych. Eto Demerzel's forces are closing in, however, so Hari, Dors, and Raych escape to the Wye sector.
Once there, they learn the Mayor of Wye has recently abdicated in favour of his daughter, Rashelle. She wishes to use Seldon and his "psychohistory" to take control of Trantor and the Inner Worlds (not caring about the entire empire as it affects her too indirectly). It takes an intuitive understanding of individual psychology to rescue Seldon now, and he's realized how to take the lessons learned here to save himself and begin true work on Psychohistory.
Prelude to Foundation provides examples of:
- Absurdly Cool City: Hari Seldon explores multiple areas of the planet-wide city Trantor, capital of the Galactic Empire, which is almost entirely enclosed and continues many kilometers underground. He travels from the Upperside of the domes to the heat sinks of the Dahl sector.
- Action Girl: Dors Venabili, a historian, is asked to protect Hari Seldon, which initially seems like it is based on her greater experience with Trantor, until they visit the neighborhood of Billibottom. Billibottom is a high-crime area where people carry illegal knives, and Venabili shows herself to be very capable with a dual knife style, taking down one of the biggest knifers and cutting off his moustache. She's also a humaniform robot, under orders from Daneel to protect Seldon so that he can develop psychohistory and protect humanity from the fall of galactic civilization.
- The Artful Dodger: Raych, a charming alley kid (his mother is briefly mentioned) in the Dahl sector, initially demands a knife as payment for leading Seldon and Venabili to Mother Rittah. Seldon is able to convince him that a computer that teaches him to read is more valuable, and pays him that way. They repeatedly have to haggle with Raych to ensure they get what they want from him, and eventually adopt him as their child.
- Artifact Title: Seldon describes his term "psychohistory" as an early misnaming, saying that it should more properly be called "psychosociology", but he liked the other name more.
- Artificial Outdoors Display: Hari Seldon goes to an indoor park on Trantor. Most native Trantorans don't go to the parks — being that close to nature freaks them out — but it's an amenity for off-worlders, who didn't grow up in a domed planet-wide city.
- Badass Bookworm: Hari Seldon, who is only known as a mathematician, is assaulted by a pair of thugs in a park in chapter 2 (and again when he visits Billibottom). At which point it turns out his entire homeworld (Helicon) knows kung fu. The style he practices is called Heliconian Twisting."Apparently, mathematics and the martial arts are not necessarily mutually exclusive." — Eto Demerzel
- Became Their Own Antithesis: The Mycogenian society claims to be descendants of Spacers (specifically the Aurorans, from The Robots of Dawn). Aurorans pictured their planet as one with full social mobility, gender equality, and a Free-Love Future. The Mycogenians, however, have a strict Fantastic Caste System, the women take the place of the Lost Technology robots, and the society is implied to be very restrictive sexually.
- Boxed Set: In 2018, Editora Aleph, a Brazilian publisher, printed Fundacao: declinio e ascensao. Roughly translated into English, this means Foundation: Decline and Ascension. Both Sequel and both Prequel novels are here; Foundation's Edge, Foundation and Earth, Prelude to Foundation, and Forward the Foundation.
- In this Prequel, gravitic elevators are described as technology that might eventually be used to make gravitic spaceships, but it is assumed to take many centuries before it could work as such. By the time of the previously published Sequel, Foundation's Edge, Terminus starts utilizing such ships, with large parts of both that book and Foundation and Earth taking place aboard one.
- In the final chapter, as Hummin and Seldon discuss how to go about using psychohistory, Hummin recommends that he uses two devices for his psychohistory plans, so that if one fails, the other can be used to carry on. Seldon would be inspired by this to create the First and Second Foundations. Hummin states to have done that himself, with the other plan being something on another planet and based on a different principle, to provide a hope for humanity in case psychohistory fails. He is referring to Gaia.
- City Planet: Trantor, capital of the Galactic Empire, is divided into approximately 800 domed cities, each with their own subcultures, with some open space in-between used for transportation, communication, cooling towers, etc. The twenty nearest inhabited planets are all agrarian economies whose primary export market is Trantor. (Prelude can be considered Asimov's attempt to reconstruct the idea of a planet-wide Mega City.) Hari Seldon goes on The Quest to find a model for psychohistory by exploring multiple areas of Trantor.
- Close-Call Haircut: Venabili manages to cut off part of Marron's moustache in their fight, after deliberately scoring several shallow cuts. She threatens that this is his last warning, and her next counterattack would be deadly. He takes the threat seriously and runs away.
- Dedication: This book is dedicated to Jennifer Brehl, for being a wonderful editor.''To Jennifer "Green Pencil" Brehl,
the best and hardest-working editor in the world.
- Encyclopedia Exposita: This novel has an Encyclopedia Galactica entry for each of the nineteen chapters, beginning with Emperor Cleon I and ending with Hari Seldon. Both Trantor (2&5) and the Mycogen sector (7&9) appear twice, and most entries are about someone Seldon meets during that chapter.
- Evil Chancellor: Chetter Hummin manages to convince Hari Seldon that Eto Demezrel, who is Emperor Cleon I's chief of staff, is working only to selfishly profit from Seldon's recent "psychohistory" paper. The audience sees Demerzel encouraging the emperor to believe that killing Seldon is preferable to allowing him to work for any other faction in the empire. Chetter and Demerzel are the same character.
- Exactly Exty Years Ago: The story begins just after the Decennial Celebration, which happens every ten years on Trantor. This Decennial Celebration takes place in 12020 G.E., making Seldon thirty-two (because he was born 10,000 years after the book's publication, in 11988 G.E.).
- Exty Years from Now: Published in 1988, this is the first story in the series to feature Hari Sheldon as The Protagonist, and his birth year is 11988 G.E. This is actually an Inverted Trope since his birthdate was chosen by Dr. Asimov when publishing Foundation (1951), and choosing to publish the prequel in 1988 is deliberately evoking the sense of taking place ten thousand years years in the future, despite Galactic Era not technically being compatible with Anno Domini (Year 1 G.E. is still thousands of years in the future).
- Fantastic Fighting Style: Hari Seldon, who is only known as a mathematician, is assaulted by a pair of thugs in a park in chapter 2 (and again when he visits Billibottom). At which point it turns out his entire homeworld (Helicon) knows kung fu. The style he practices is called Heliconian Twisting.
- Hereditary Republic: The Mayor of Wye is somehow a hereditary title, and until he abdicated in favour of Rashelle, it was ruled by Mannix IV.
- Hugh Mann: The name "Chetter Hummin" ("Cheater Human") is a clue that Seldon notices means Hummin isn't actually human. The pun helps him avoid the psychological cost of lying to humans; lying is an indirect violation of the Three Laws of Robotics. From this, and other oddities, Seldon realizes that Hummin is actually R. Daneel Olivaw.
- Interquel: Because this book was written after this series was tied to the three Galactic Empire novels, it fits between both that Trilogy and The Foundation Trilogy. However, it was primarily marketed as a Prequel to the Foundation series.
- King Bob the Nth:
- Emperor Cleon I, current ruler of the Galactic Empire. He is the namesake to Emperor Cleon II, from "The General (Foundation)".
- Emperor Stanel VI is Cleon's immediate predecessor, having been mentioned before in "The General (Foundation)".
- The Mayor of Wye is somehow a hereditary title, and until he abdicated in favour of Rashelle, it was ruled by Mannix IV.
- Magnificent Moustaches of Mexico: The men of the Dahl sector all wear black moustaches; it's a sign of adulthood and they're grown as thick as possible, usually with handlebar curves. When Venabili cuts off part of Marron's moustache, she also takes a bit of lip by accident, ensuring that he'll never be able to regrow that manhood. Dahl is an oppressed sector of the enormous Trantor City Planet, where the population is considered good only for dirty labour, much like an American stereotype of Hispanics.
- Magnetic Hero: Raych is shown to be charming and quick-witted from the beginning, with both Hari and Dors liking the streetwise urchin even though they barely know him. His charm contributes to his ability to stop Mayor Rashelle of sector Wye from killing Hari. This turns out to be an incipient form of the mental powers Raych's daughter, Wanda, ends up developing.
- Mix-and-Match Weapon: One of the two lackeys that tried to attack Seldon in the open-air park had a knife with a "laser inset" (it isn't elaborated whether it is a Laser Blade, some enhancement function to the metal or perhaps an inbuilt gun). Hummin and Seldon find this distasteful, since knives are still effective by themselves.
- Modesty Towel: The day after their second trip to Billibottom, Seldon interrupts Venabili not long after her morning ablutions, He's only dressed from the waist down, and so is she. He's initially embarrassed by seeing her this way, while she carelessly begins to dry her hair with a towel. After the initial awkwardness, Hari simply speaks directly to her.
- Multicultural Alien Planet: Hari Seldon doesn't believe his psychohistory mathematics can be very useful. He'd need a model so diverse that it's essentially as complicated as the galaxy. R. Daneel Olivaw arranges for him to run throughout the Layered Metropolis of the City Planet Trantor so that he realizes that it fits the description. It has people from the three major ethnicities (Westerners, Southerners, and Easterners) and each of the hundreds of sectors are like a world of their own.
- Naming Your Colony World: Helicon, homeworld of Hari Seldon, shares its name with a mountain from Greece (and Greek Mythology). In myth, the mountain is host to the Muses. This can also be seen as symbolic, as Seldon is the "poet" inspired to create psychohistory and the Seldon Plan.
- Only One Name:
- Raych is too poor to have anything more than one name (not that he minds).
- Davars is using a false identity, and only assumes the one name.
- The Plan: Prelude to Foundation: Chetter Hummin convinces Hari Seldon to run away from the Evil Chancellor, causing him to hide amoung various factions of people living on Trantor. Mr Hummin is actually R. Daneel Olivaw, and so is the Chancellor. He orchestrated this to help Seldon develop psychohistory.
- Prequel in the Lost Age: Prelude to Foundation and Forward the Foundation are both Prequel stories to The Foundation Trilogy, taking place in the heart of the First Galactic Empire, before the collapse became apparent due to the independence of the Periphery worlds.
- The Quest: Chetter Hummin convinces Hari Seldon to begin seeking a way to make psychohistory practical. At the same time, Seldon tries to keep away from the influence of people who wish to use him as a figurehead, pretending the problems of psychohistory have been solved so that they can gain more power. Seldon travels to the Streeling University, Mycogen, and Dahl sectors of Trantor to keep ahead of Emperor Cleon I's chief of staff, Eto Demezrel.
- Ridiculously Human Robots:
- Several stories are told about Daneel Olivaw, a robot that looks indistinguishable from a human being. Those who believe themselves descendants of the Spacers hate him, labeling him as a Renegade. Those who believe themselves to be descendants of the Settlers label him as the one good robot, and all others are the work of evil. The character and the ancient tales derive from Robots and Empire. Daneel has assumed multiple identities in the intervening millennia, including Eto Demerzel and Chetter Hummin.
- Secretly, there is also Dors Venabili, a female humaniform robot, assigned to Hari Seldon's protection by Hummin. Dors eventually develops genuine love for Seldon and actually violates the First Law to protect him.
- Robotic Reveal:
- Hari Seldon infers that Dors Venabili is actually a robot, because they have inhuman reflexes and learning, as well as the ability to communicate to Chetter Hummin without any equipment. However, he doesn't really care if they're human or not and even if she can't experience love, he marries her.
- Hari Seldon figures out that Chetter Hummin, also known as Eto Demerzel and R(obot) Daneel Olivaw, is actually a robot due to the way they are so unnaturally persuasive and the stories he's heard about Daneel Olivaw while running around the sectors of Trantor.
- Running Gag: The sector of Wye causes confusion on several occasions, since "Wye" sounds like "why".
- Self-Fulfilling Prophecy: Demerzel and Emperor Cleon Discuss the idea of a prediction that comes true by telling people about it. Seldon later deconstructs the idea by explaining to the Emperor that such a prophecy must be made too vague and remote for people to care about, or so specific that it could easily prove false. When the mayor of sector Wye captures him, it's once again a "self-serving" prophecy that is demanded of Seldon."You don't need to predict the future. Just choose a future-a good future, a useful future-and make the kind of prediction that will alter human emotions and reactions in such a way that the future you predicted will be brought about. Better to make a good future than predict a bad one." — Emperor Cleon I
- Silly Reason for War: Hari Seldon mentions a youth subculture conflict on his home planet. Some youths shave their head on one side and allow the other side to grow long, but the ones who shave their right side can't stand the ones who shave their left side, and vice-versa.
- Single Line of Descent: When Rashelle, Mayor of sector Wye, claims that she should be the Empress because her family descends from the ancient ruling house of Dacian. Venabili, a historian, remarks that said dynasty ruled 5,000 years ago, which means half of the galaxy can claim to be descendants.
- The Smurfette Principle: In the Sequel, Forward the Foundation, when Seldon thinks back to this story, he believes that he only met four people during his Flight across Trantor; Demerzel (a male robot), Yugo Amaryl (a male mathematician), Raych (a young boy from the alleys), and Dors Venabili (a female historian). He's wrong; he meets several other people, both male and female, but these people (and Emperor Cleon I) are the only ones who persist across both volumes.
- Space Amish: The inhabitants of Mycogen sector on Trantor, who believe themselves to be the last descendents of Spacers from Aurora and live a rather ascetic lifestyle, while basically worshiping the memory of the lost paradise worlds of their ancestors.
- Spy Speak: When Venabili and Seldon catch a private air-jet, Hummin has set up a sign/countersign code based on Seldon's nascent mathematical theory (psychohistory).Dors said, "We're psycho."
The pilot said, "And I'm history."
- Star-Crossed Lovers: When she was younger, Rashelle of Wye — the daughter of the highest-ranking aristocrat in one of Trantor's richest sectors, whose family claims royal ancestry — had a boyfriend from Dahl, the planet's poorest and lowest-class sector. Her father forced her to dump him, but she still clearly remembers the relationship fondly, which contributes to her taking an instant liking to Raych. Dors later cites this as one of the reasons she feels sorry for Rashelle, even as she plots to overthrow the Empire.
- Three Laws-Compliant: Always a motivation for his humaniform robots, Dors Venabili and Daneel Olivaw are constrained by these rules without being obvious about it. The first robot is able to create superficial harm to humans due to a highly stressed Second Law reinforcing the First Law (protect this specific human from harm). The second robot rationalizes the need to use their Psychic Powers on people to protect his existence (Third Law) as well as Seldon's (First Law).
- Torn Apart by the Mob: One of the attempts to get Hari Seldon to the Emperor involved tempting him to commit an act of sacrilege in an extremely religious community, and then offer him a choice between an appeal to the Emperor and this trope.
- Two Aliases, One Character: Cleon I's Chief of Staff, Eto Demerzel, is hiding a secret identity; he's actually R. Daneel Olivaw, from Robots and Empire. Chetter Hummin is suspicious of him, and tries to help Hari Seldon avoid the man behind the throne, because Eto is hiding secrets and will want to use Seldon's work for selfish reasons. This works up until the climax, when Seldon encounters Eto Demerzel directly, and realizes that Chetter Hummin is a false identity used by Demerzel to control his actions all along. The identity (Chetter Hummin) is a pun — he's cheating at being human — because he's a robot.
- Two Words: Added Emphasis: Chetter Hummin claims to know the truth of humanity's situation, and can put it into five words; "The Galactic Empire is dying." He's trying to convince Hari Seldon that his "psychohistory" is needed for the sake of humanity's future.He then spoke those five words grimly.
He said, "The Galactic Empire is dying."
- Uncovering Relationship Status: Hari Seldon tries to discover if Dors Venabili is in a relationship with Hummin by asking if she knows him intimately. She takes offense at his impertinence and implication that a relationship would make her "his". Shes an independent woman and doesn't "belong" to anyone, thank-you-very-much.
- We Will Have Euthanasia in the Future: Hummin points out that there are no legal barriers to committing suicide on Trantor, and there are several places that cater to such desires (however, psychological screening is required before euthanasia will be administered, presumably to ensure you are mentally competent to make that descision).
- Who's on First?: Beginning in chapter 7, there's a Running Gag that an important region on Trantor, called Wye, is pronounced the same as "why", causing miscommunication amoung the characters. One such confusion/joke strikes at the end, when Seldon, alongside Dors and Raych, are taken there. They ask where they are being held, and the one who is keeping them prisoner tells them "Wye", which sounds like they're avoiding the answer."Wait, Madam," said Dors. "May I ask where we are?"
"Wye, dear. And please call me Rashelle, as you come to feel more friendly. I am always at ease with informality."
Dors stiffened. "Are you surprised that we ask? Isn't it natural that we should want to know where we are?"
Rashelle laughed in a pleasant, tinkling manner. "Really, Dr. Venabili, something must be done about the name of this place. I was not asking a question but making a statement. You asked where you were and I did not ask you why. I told you, 'Wye.' You are in the Wye Sector."
- 'You Are Number 6: The Mycogen sector of Trantor have a "cohort" (family) name and a number for first name, like Mycelium 72, Raindrop 43, Raindrop 45, and Sunmaster 14.