In Harry Potter’s magical world, nothing is as it seems—and that goes for the books themselves. Woven into the tales are all kinds of mysterious meanings, surreptitious signs and cloaked clues that, when deciphered, illuminate the themes of the story. Those cool tidbits and Harry Potter facts are part of what has made these some of the best books ever written.

Harry Potter has its own universe complete with timelines, histories, connections and Easter eggs that are like little puzzles for fans to pick up on and put together. So naturally, we went down the rabbit hole—or to use a Harry Potter metaphor, into the Pensieve—to dig up the secret messages in the Harry Potter canon. We mainly stuck to what is written into the books themselves or specially noted by author J.K. Rowling, but we did throw in a couple of particularly intriguing fan theories, plus a few tidbits from the movies.

Be forewarned: While even people who haven’t read the books know a little something about Harry Potter—it is the bestselling book series in history, after all!—this story isn’t for Muggles. (It also isn’t for those who’ve never read the books; suffice it to say there are major spoilers ahead.) Only true fans will appreciate this deep dive into the world of the boy wizard.

So wands at the ready! Read on to find out the most secret of all Harry Potter facts.

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1. Sirius Black shows up in the first chapter of the first book

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One of the most genius aspects of the books is how they weave in seemingly unimportant, throwaway details that become much more important later—and not just later in that book. Rowling sets the stage early for a payoff later in the seven-part series.

For example, here’s our first piece of Harry Potter trivia: Sirius Black, Harry’s godfather and a hugely important figure who doesn’t appear in person until book three, Harry Potter and the Prisoner of Azkaban, is mentioned in the very first chapter of the very first book, Harry Potter and the Sorcerer’s Stone.

On the night Harry’s parents are killed, Hagrid delivers Harry to Professor Dumbledore at the house of Harry’s Muggle relatives, the Dursleys—on a motorcycle. When Dumbledore asks where he got it, Hagrid says, “Young Sirius Black lent it to me.” By the time they meet Sirius two books later, most readers would have forgotten where they’d heard the name before.

2. Harry’s first two father figures represent opposites

Colors and name meanings, which are huge in Harry Potter, first come into play with the two father figures of orphaned Harry that readers meet in the first chapter of Sorcerer’s Stone: Rubeus (or “red”) Hagrid and Albus (or “white”) Dumbledore. In an author’s note on the official Wizarding World website (formerly Pottermore), Rowling points out that red and white are complementary colors in the mystical science of alchemy and represent different stages of spiritual transformation.

“I named them for the alchemical colors to convey their opposing but complementary natures: Red meaning passion (or emotion), white for asceticism; Hagrid being the earthy, warm and physical man, lord of the forest; Dumbledore the spiritual theoretician, brilliant, idealized and somewhat detached,” she wrote. “Each is a necessary counterpoint to the other as Harry seeks father figures in his new world.”

3. Snape’s first words to Harry were about his mother

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The Harry Potter novels are supposed to be children’s books, but the symbolism is often way more sophisticated. For example, Harry Potter employs floriography, a means of communicating through flowers that was a pastime popular with the Victorians. So the first words that cold Professor Snape says to Harry in Sorcerer’s Stone—”What would I get if I added powdered root of asphodel to an infusion of wormwood?”—aren’t just a way to humiliate Harry by asking him about a potion he hasn’t learned yet.

Asphodel, a real-life flower, is a type of lily and means “my regrets follow you to the grave.” Snape, who was in love with Harry’s mother, Lily, is telling Harry he bitterly regrets her death. (By the way, Snape reveals that the answer to the question is Draught of Living Death, which Professor Slughorn’s class attempts to make in Harry Potter and the Half-Blood Prince.)

4. All the potion ingredients in Snape’s three questions are real

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Snape goes on to ask Harry two more questions: “What is the difference, Potter, between monkshead and wolfsbane?” and “Where would you look if I told you to find me a bezoar?” Although these queries sound like nonsense meant to trip Harry up in his first potions lesson, the ingredients in Snape’s list aren’t made up. In addition to asphodel, wormwood, monkshead and wolfsbane are all real plants.

As for a bezoar, as Snape correctly explained, it is “a stone taken from the stomach of a goat.” The stones form from indigestible material, such as hair, that collects in the stomach and creates a mass. From the Persian word for “antidote,” bezoars were thought to be a poison cure, which is why Snape says it can save people from most poisons. This lesson comes in handy when Harry uses a bezoar to do exactly that for his friend Ron in Half-Blood Prince.

5. Names reveal the characters’ true natures

The hidden meaning of some characters’ names gives readers clues to their inner motivations and feelings. Harry’s nasty classmate Draco Malfoy and the evil dark wizard Lord Voldemort both take their name meanings from French words. In French, mal foi means “bad faith,” fitting for a character whose family follows He-Who-Must-Not-Be-Named. Voldemort’s name comes from the French vol de mort, or “flight of death,” which makes sense as he fears dying and does everything in his power to gain immortality.

Of course, as Harry Potter and the Chamber of Secrets reveals, “I am Lord Voldemort” is also an anagram of the Dark Lord’s original name, Tom Marvolo Riddle.

Another of the most surprising Harry Potter facts we came across: In accordance with French pronunciation, Rowling revealed the last “t” in Voldemort is silent, meaning we’ve been saying it wrong all these years.

6. Names also hint at plot points

In many cases, if you know Harry Potter names’ hidden meanings, you can uncover the plot. For example, in Prisoner of Azkaban, beloved teacher Remus Lupin is discovered to be a werewolf. Remus’s first name refers to the Roman myth of Romulus and Remus, two brothers who were raised by wolves. And Lupin comes from the Latin word lupinus, meaning “wolfish.”

Wolfsbane, the real-life plant first mentioned by Snape, was once used to kill wolves. In Harry Potter, Snape uses it to make a potion to ease Professor Lupin’s werewolf symptoms.

7. Lupin’s condition is a metaphor for HIV

Speaking of Lupin, Rowling revealed a deeper layer to his werewolf disease and the secrecy surrounding it. “Remus Lupin’s affliction was a conscious reference to blood-borne diseases such as the HIV infection, with the attendant stigma,” Rowling wrote on the Wizarding World site. “The potion Snape brews him is akin to the antiretroviral that will keep him from developing the ‘full-blown’ version of his illness.”

Unfortunately, the discrimination Lupin unfairly faces when his condition is made public is the reason he has to leave Hogwarts. “The sense of ‘apartness’ that the management of a chronic condition can impose on its sufferers was an important part of Lupin’s character,” Rowling wrote. In the book-to-movie adaptation of Prisoner of Azkaban, Lupin’s condition is presented as an illness, so he appears pallid, tired and unwell.

8. Mirrors are the windows to the soul

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Alice in Wonderland isn’t the only book where looking glasses are significant—in the wizarding world, they reflect crucial truths about the characters. First, in Sorcerer’s Stone, Harry becomes entranced by the image of himself with his parents in the Mirror of Erised (desire spelled backward). In another of Dumbledore’s cheery lines, he says he sees himself “holding a pair of thick, woolen socks” when he looks in the Mirror of Erised. “One can never have enough socks,” he says. Of course, he may not have been quite truthful: Rowling has said that, like Harry, Dumbledore really sees his family reunited and happy.

But that’s not the only important mirror. In Harry Potter and the Goblet of Fire, Harry comes across a Foe-Glass, which reveals your enemies.

And in Harry Potter and the Order of the Phoenix, Sirius gives Harry a two-way mirror so they can communicate. Harry shatters it, but later, he sees an eye staring back at him in a shard. Harry discovers the eye belongs to Dumbledore’s brother, Aberforth, who helps him to safety using the mirror in Harry Potter and the Deathly Hallows.

Be on the lookout for random mentions of cracked mirrors throughout the series.

9. Bathrooms are a required room in the Harry Potter books

We don’t know exactly why this is, but bathrooms seem really, really important in Harry Potter. Nearly every book has a major scene taking place in the “loo,” as the British call it: the troll fight in Sorcerer’s Stone; the home of ghost Moaning Myrtle and the entrance to the Chamber of Secrets in, naturally, Chamber of Secrets; Harry solving a Triwizard Tournament clue in a bathtub in Goblet of Fire; Harry’s wand battle with Draco in Half-Blood Prince.

And one of the first hints of the hidden Room of Requirement, which changes to fit the seeker’s needs, is Dumbledore finding a room full of chamber pots when he had to go the bathroom in Goblet of Fire. A sly reference to this shows up as one of the funniest Harry Potter quotes in the movie version of Half-Blood Prince, courtesy of Ron, as Hermione explains the Room of Requirement: “So say you really needed the toilet?” he asks. “Charming, Ronald. But yes, that is the general idea,” Hermione replies.

Perhaps this potty preoccupation exists because “Hogwarts didn’t always have bathrooms,” revealed by the official Wizarding World on X, which caused a fan frenzy. “Before adopting Muggle plumbing methods in the 18th century, witches and wizards simply relieved themselves wherever they stood and vanished the evidence.” Gross!

10. Riddle’s diary almost never made it to Hogwarts

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All readers know that Tom Riddle’s diary, which is later revealed to be a Horcrux where Dumbledore keeps a part of his soul, allowed him to open the titular chamber inside Hogwarts in Chamber of Secrets. It’s also no secret that Lucius Malfoy gave Ginny Weasley the diary before the start of school at the Diagon Alley bookshop Flourish and Blotts.

But probably one of the most surprising Harry Potter facts to come out of the books is that the diary almost didn’t make it to Hogwarts! Leaving the Burrow for the Hogwarts Express, the Weasley family had to keep turning back because they’d forgotten something: First George forgot his box of Filibuster Fireworks, then Fred forgot his broom, then “they had almost reached the motorway when Ginny shrieked that she’d left her diary.” If they hadn’t gone back to get it, the chamber would never have been opened.

11. Random objects turn out to be important

It’s just about impossible to know what’s going to be important later on in the Harry Potter books, which is part of why they’re some of the best fiction books ever written. For example, in Order of the Phoenix, Harry, Ron and Hermione come across a locket while cleaning out Grimmauld Place, which later ends up being a Horcrux: “There was a musical box … also a heavy locket that none of them could open, a number of ancient seals and, in a dusty box, an Order of Merlin, First Class.”

In Half-Blood Prince, when Harry hides his copy of Advanced Potion-Making in the Room of Requirement, he uses yet another Horcrux, the lost diadem (or tiara) of Ravenclaw, to mark the spot: He “perched a dusty old wig and a tarnished tiara on the statue’s head to make it more distinctive.”

Possibly the most important objects that are mentioned several times throughout the series are the vanishing cabinets that Draco Malfoy uses to sneak Voldemort’s followers, the Death Eaters, into Hogwarts in Half-Blood Prince. They first pop up in Chamber of Secrets: Harry hides in the one in the antique shop Borgin and Burkes, and poltergeist Peeves drops the one at Hogwarts to distract caretaker Filch. Then in Order of the Phoenix, Fred and George Weasley force a Slytherin named Montague “into that Vanishing Cabinet on the first floor.” This ends up being a huge mistake because Montague’s tale of the incident gives Draco the idea to use it to sneak in Death Eaters, as he explains to Dumbledore right before his death in Half-Blood Prince.

12. Seven is the most powerful number

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In numerology, numbers have mystical meanings. The same is true in Harry Potter—it’s part of what makes this one of the best fantasy book series. Lucky number seven, for example, pops up everywhere: seven Potter books, seven children in the Weasley family, seven players on a Quidditch team, seven years at Hogwarts, seven Horcruxes containing pieces of Voldemort’s soul and more. In Hogwarts lore, a 13th-century witch named Bridget Wenlock (who appears in the official Harry Potter video game, The Book of Spells) was the first to discover the magical properties of seven.

Another number that pops up often? The trinity, or number three: three Deathly Hallows, three unforgivable curses, the three-headed dog, three tasks and three schools in the Triwizard Tournament, and the core trio of Harry, Ron and Hermione.

13. Number 13—even chapter 13—is unlucky

Another important number is unlucky even in the wizarding world: 13. In that chapter of each book, an evil character or Horcrux is often introduced or becomes crucial to the plot. Think: Tom Riddle’s diary appearing in Chamber of Secrets, Mad-Eye Moody (really Barty Crouch Jr. in disguise) performing magic on a student in Goblet of Fire and Harry’s first detention with Umbridge in Order of the Phoenix.

The kooky divination teacher, Professor Trelawney, also references the nefarious powers of 13 by initially refusing an offer to join Christmas dinner in Prisoner of Azkaban. “If I join the table, we shall be thirteen! Nothing could more unlucky! Never forget that when thirteen dine together, the first to rise will be the first to die!” she says. However, there were probably already 13 at the table, thanks to Peter Pettigrew, who was still transformed as Ron’s pet rat, Scabbers. (He’s not explicitly stated to be there, but it’s likely.)

As for Trelawney’s statement that the first of 13 diners to rise will die first? It’s an accurate prediction. Dumbledore rose when Trelawney appeared—and is the next to die. This also holds true later: Sirius rises first at supper at Grimmauld Place in Order of the Phoenix, and Lupin does so at a gathering to mourn Mad-Eye Moody in Deathly Hallows.

14. Trelawney’s predictions come true

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Despite Dumbledore saying Trelawney has only made two correct prophecies, other predictions that readers may think are just her silly ramblings actually come to pass. For example, in Goblet of Fire, Trelawney guesses Harry’s birthday is in midwinter, which, of course, is wrong; Harry was born in July, so it seems like a funny joke. But there might be a hidden meaning behind the prediction: Guess who was born in midwinter, on New Year’s Eve to be exact. As noted in Half-Blood Prince, it’s Voldemort. And as we now know, part of Voldemort’s soul resides in Harry.

Still not convinced Trelawney was a real seer? How about her prediction for Dumbledore’s death in Half-Blood Prince: “‘Again and again, no matter how I lay them out—’ And she pulled a card dramatically from underneath her shawls. ‘—the lightning-struck tower,’ she whispered. ‘Calamity. Disaster. Coming nearer all the time.'” That same night, Dumbledore dies, in a chapter called “The Lightning-Struck Tower.”

15. Harry and Ron’s predictions come true too

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Like Trelawney, Ron and Harry might possess more of the Inner Eye than readers think. Take these supposedly made-up predictions from Goblet of Fire: “OK … on Monday, I will be in danger of—er—burns,” Harry says. When thinking up predictions for Tuesday, Ron suggests, “Why don’t you get stabbed in the back by someone you thought was a friend?”

Unfortunately for Harry, these things actually do come to pass. He’s risking burns when he faces a dragon in the first Triwizard task and later, Ron stabs him in the back by jealously refusing to speak to him.

16. Ron’s joke about Tom Riddle is spot-on

Even some of the Harry Potter jokes throughout the books have an element of truth—in some cases, they’re completely correct! In Chamber of Secrets, Harry, Ron and Hermione wonder what Tom Riddle (aka Voldemort) did to receive a Special Award for Services to the School. Ron throws out this goofy speculation: “Maybe he got thirty O.W.L.s or saved a teacher from the giant squid. Maybe he murdered Myrtle; that would’ve done everyone a favor.”

But Riddle did kill Moaning Myrtle, the student who is now a Hogwarts ghost, when he opened the Chamber of Secrets and released the basilisk. Good one, Ron!

17. Fred and George’s pranks are also useful

They might not be the funniest books ever, but the Harry Potter novels get in their fair share of laughs. In Sorcerer’s Stone, Ron’s brothers Fred and George take aim—literally—at an unsuspecting Professor Quirrell: “The lake froze solid and the Weasley twins were punished for bewitching several snowballs so that they followed Quirrell around, bouncing off the back of his turban.” At this point in the story, Voldemort is sharing Quirrell’s body, with his face on the back of Quirrell’s head hidden underneath the turban.

That means technically, the Weasley twins were hitting Voldemort in the face with snowballs! It’s just like the jokesters to pull a prank like that, even if they didn’t realize it. Lucky for them, Voldemort couldn’t fight back.

18. Harry bears a resemblance to another “chosen one”

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A sword with magical powers that can only be summoned by a special someone … nope, we’re not talking about the sword of Gryffindor but the legendary King Arthur’s Excalibur, the stuff of fairy tales. If Harry’s sword is Excalibur, does that mean Harry is King Arthur? Arthur, after all, was also an orphan from humble beginnings who was chosen to possess a powerful sword and become a leader. (Dumbledore could double as Arthur’s wizard mentor, Merlin, and Hogwarts could be Camelot.)

“Gryffindor’s sword owes something to the legend of Excalibur, which in some legends must be drawn from a stone by the rightful king,” Rowling said on the Wizarding World site. “The idea of fitness to carry the sword is echoed in the sword of Gryffindor’s return to worthy members of its true owner’s house.”

The sword of Gryffindor plotline includes another intentional throwback to Arthurian legend. “There is a further allusion to Excalibur emerging from the lake when Harry must dive into a frozen forest pool to retrieve the sword in Deathly Hallows,” Rowling said. “In other versions of the legend, Excalibur was given to Arthur by the Lady of the Lake and was returned to the lake when he died.”

19. Dumbledore’s password is his favorite treat

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Just as we might use our childhood pet’s name as our computer password, Dumbledore’s strategy for the password to his secret office staircase is his favorite sweet. This treat is mentioned in the very first chapter of Sorcerer’s Stone, when Dumbledore offers one to Professor McGonagall. “Would you care for a sherbet lemon?” he asks a befuddled McGonagall, going on to explain it as “a kind of Muggle treat I’m rather fond of.”

Then in Chamber of Secrets, when Harry enters Dumbledore’s office for the first time, McGonagall uses the words sherbet lemon as the password. In the American version of the books, both of these were changed to lemon drop, but in the Harry Potter movie version of Chamber of Secrets, McGonagall still says “sherbet lemon.”

The next time the password shows up is in Goblet of Fire, when Harry urgently needs to see Dumbledore and tries it again, without success, so he guesses other sweets. “‘Sherbet lemon?’ he tried tentatively. The gargoyle did not move. ‘OK,’ said Harry, staring at it. ‘Pear drop. Er—Liquorice wand. Fizzing Whizzbee. Droobles Best Blowing Gum, Bertie Botts’ Every Flavor Beans … oh no, he doesn’t like them, does he?'”

The guessing game continues with this amusing outburst: “‘Chocolate Frog!’ he yelled angrily, standing on one leg. ‘Sugar quill! Cockroach cluster!’ The gargoyle sprang to life and jumped aside. Harry blinked. ‘Cockroach cluster?’ he said, amazed. ‘I was only joking.'” Fun fact: Cockroach clusters are a treat from a Monty Python’s Flying Circus sketch.

20. Chocolate Frog cards may be spies

We know the collectible Chocolate Frog cards are important, and not just as a possible password—in Sorcerer’s Stone (the book version), info on Dumbledore’s card is where Harry learns of alchemist Nicolas Flamel.

But that might not be the only reason the collector’s items are critical to the story. In Order of the Phoenix, Dumbledore seemingly jokes about the cards, as Ron’s brother Bill relates: “Dumbledore says he doesn’t care what they [the Ministry of Magic] do as long as they don’t take him off the Chocolate Frog Cards.” It seems like a throwaway joke, but could it be that the portraits on the cards are acting as spies and passing secret information? A fan theory suggests so.

We’ll bite.

Readers know the portraits that hang on walls convey secret messages in Deathly Hallows. Like these portraits, we know the card images are capable of leaving their frames: In Sorcerer’s Stone, when Harry gets his first Dumbledore card on the Hogwarts Express, he’s surprised when Dumbledore’s image disappears. “Well you can’t expect him to hang around all day,” Ron says. “He’ll be back.” We also know Dumbledore somehow knows about everything that goes on at Hogwarts. So maybe Dumbledore feared losing his Chocolate Frog card for a more important reason. Interesting theory!

21. Aberforth appears before Deathly Hallows

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Chocolate Frogs might not be the only way Dumbledore gets his information. In Deathly Hallows, readers meet his brother, Aberforth, the bartender of the Hog’s Head who becomes important to the resistance. But he was actually referred to throughout the book series—even though readers might have glossed over it.

His first mention by name is in Goblet of Fire when, in an effort to cheer up Hagrid after being outed as a giant, Dumbledore says, “My own brother, Aberforth, was prosecuted for practicing inappropriate charms on a goat.” Later in the series, we find out Aberforth’s patronus (a sort of anti-Dementor guardian that wizards can cast) is a goat.

Aberforth is also hinted at, although not by name, many times. When Harry first enters the Hog’s Head in Order of the Phoenix, he mentions it smells of goats and the bartender looks familiar. Later, he says he thought the barman was listening.

In Half-Blood Prince, Harry recognizes the barman from the Hog’s Head with thief Mundungus Fletcher in Hogsmeade (likely buying the two-way mirror, which becomes important in the final book). And in a Half-Blood Prince flashback memory, Tom Riddle/Voldemort tells Dumbledore he is “as omniscient as ever.” “Oh no, merely friendly with the local barmen,” Dumbledore retorts.

Later, at Dumbledore’s funeral, the list of the “extraordinary assortment of people” includes the barman of the Hog’s Head. Most important, Aberforth thwarted Snape from overhearing the whole of Trelawney’s initial prediction about Harry at the Hog’s Head years ago. She remembers in Half-Blood Prince, “There was a commotion outside the door, and it flew open, and there was that rather uncouth barman standing with Snape.” Readers think this is important because Harry learns the eavesdropper was Snape, but the barman was another crucial, hidden tidbit.

22. Dementors personify depression

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The soul-stealing Dementors, creatures that suck hope and happiness out of anyone they’re near and that first appear in Prisoner of Azkaban, are a physical manifestation of what it’s like to experience depression. “It’s so difficult to describe [depression] to someone who’s never been there because it’s not sadness,” Rowling said in an interview with Oprah Winfrey. “Sadness is to cry and to feel. But it’s that cold absence of feeling—that really hollowed-out feeling. That’s what Dementors are.”

For Harry, Dementors also cause him to relive the trauma of his mother’s death at the hands of Voldemort: When Dementors are near, he hears her screams.

23. The Marauder’s Map contains a plot clue

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We solemnly swear we’re up to no good! The Marauders Map lists its creators as “Messrs. Moony, Wormtail, Padfoot and Prongs,” who of course refer to Remus Lupin, Peter Pettigrew, Sirius Black and Harry’s father, James Potter. Interestingly, the Marauders died in the reverse order of the way they are listed on the map: James before the events of Sorcerer’s Stone, Sirius in Order of the Phoenix, Pettigrew in Deathly Hallows and Lupin at the end of that same book. Coincidence? Possibly, but it still makes you raise an eyebrow.

24. The Black family has a celestial theme

Speaking of Sirius and the noble house of Black, many of his family members are named after constellations. Although Harry Potter doesn’t delve deep into the divine art of astrology beyond what Trelawney teaches, the stars do seem to have meaning, particularly for the Blacks. The most significant is Sirius himself, with the star Sirius often called the “Dog Star” and serving as a prominent part of the constellation Canis Major (translation: “greater dog”), which makes sense considering Sirius can turn into a dog.

But there’s also Sirius’s evil cousin Bellatrix (a star in the Orion constellation whose name means “female warrior”); her sister and Tonks’s mother, Andromeda (the “chained maiden”); Sirius’s brother, Regulus (“little king”); and their uncle Alphard (a star in the snake-like constellation Hydra that means “solitary one”).

25. The house colors represent the elements

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Here’s some more color symbolism: Everyone knows that students are sorted into the four houses of Hogwarts based on their personalities—Gryffindors are brave, Ravenclaws are clever, Hufflepuffs are loyal and Slytherins are, well, sneaky. But did you know the house colors have a deeper meaning connected to these values? If you read a lot of zodiac books, you may have an inkling of where we’re going with this.

“The four Hogwarts houses have a loose association with the four zodiac elements, and their colors were chosen accordingly,” Rowling wrote on the Wizarding World site. “Gryffindor (red and gold) is connected to fire; Slytherin (green and silver) to water; Hufflepuff (yellow and black, representing wheat and soil) to earth; and Ravenclaw (blue and bronze; sky and eagle feathers) to air.”

The fire symbolism is particularly interesting for Gryffindor, as it’s also connected to Fawkes, Dumbledore’s phoenix, which occasionally burns up only to be reborn from the ashes. Dumbledore himself was in Gryffindor, as Hermione says when they first meet her on the Hogwarts Express in Sorcerer’s Stone. What’s more, his patronus is a phoenix, which Harry confirms in Deathly Hallows.

26. Wizards may drink Starbucks

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The books aren’t the only places secret messages turn up. Look closely in the Order of the Phoenix film, and you’ll see what looks like a Starbucks logo at the bottom of the Black family tapestry in Sirius’s family home and Order of the Phoenix safe house, 12 Grimmauld Place. Could the filmmakers be paying homage to the fact that Rowling wrote the early books in coffee shops (although she never actually wrote at a Starbucks)? Perhaps the tapestry’s creators at graphic design firm MinaLima were just really in need of caffeine.

Here’s the most likely explanation: Both the Starbucks logo and the tapestry are referencing the same thing: the siren, a mythical mermaid-like creature often depicted with a crown and two tails. Sirens are called “the oldest recorded merpeople” in the short book Fantastic Beasts and Where to Find Them, a Harry Potter companion.

27. Nicolas Flamel was a real person

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As we’ve seen, the author’s use of Greek mythology, legends, ancient languages, botany and astronomy in creating the world of Harry Potter is magical in itself, particularly since some of the objects, places and even people are actually real—although not all the details are.

In Sorcerer’s Stone, Nicholas Flamel, who was over 600 years old, is the only known maker of the titular object, which can grant immortality. In real life, Flamel was a medieval scholar, philanthropist and alchemist who did, in fact, pursue the legendary stone—but he died in 1418.

By the way, alchemy was real too: A medieval forerunner to modern chemistry, alchemy was concerned with the transformation of substances through experimentation. Its practitioners also explored the spiritual and mystical aspects of transformation, which is why they were called philosophers, as in the British title of the first book, Harry Potter and the Philosopher’s Stone. Alchemists did, in real life, search for ways to make the stone and to transform lead into gold.

28. Mandrakes are a real plant

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In Chamber of Secrets, Harry and his fellow herbology students learn about mandrakes, whose roots take on human form and whose cries can kill you. Although they aren’t deadly (unless potentially ingested at high doses), mandrakes are real plants—and their roots do look like small human bodies.

Native to the Mediterranean region and the Middle East, mandrakes were used for their medicinal properties. Harry Potter isn’t the first reference to their supposedly fatal cries, as legend has it that the plant’s screams can cause insanity and death. Shakespeare even mentions them in Romeo and Juliet: “…shrieks like mandrakes torn out of the Earth, that living mortals, hearing them, run mad.”

29. Dumbledore looks triumphant after Voldemort’s return

One line in Goblet of Fire has long puzzled readers: Why, after Harry tells how Voldemort used Harry’s blood to create a new body, did Harry think he saw a fleeting “gleam of something like triumph in Dumbledore’s eyes”? Was the old wizard happy that Voldemort had returned? No, but he was happy about the way he did it because he knew it would protect Harry in the long run, as he reveals in Deathly Hallows.

At the end of the final book, when Harry is between life and death and talks with Dumbledore, he asks his mentor how he can be alive after Voldemort used the killing curse on him this time. “He took your blood and rebuilt his living body with it! Your blood in his veins, Harry, Lily’s protection inside both of you! He tethered you to life while he lives!” Dumbledore says. That explains his triumphant look three books earlier.

30. Platform 9 3/4 may contain a secret meaning

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Just when does Harry Potter take place? Clues to the timeline may exist in the naming of Platform 9 3/4, the magical place where the Hogwarts Express leaves. The wizards access it from inside King’s Cross Station, a very real place in London. Disclaimer: The platform’s meaning has never been confirmed, but this is too good not to mention!

We know from the tombstones in Deathly Hallows that the timeline of Harry Potter begins on Oct. 31, 1981, when Harry’s parents were killed and Harry got his scar from Voldemort. Readers also had a clue to the timeline from an earlier book: In Chamber of Secrets, the ghost of Sir Nicholas celebrated his 500th death day, which his cake specified took place on Oct. 31, 1492. Halloween is an important, if deadly, day in Harry Potter!

Let’s doing the math: The second book takes place in 1992, when Harry is 12. Therefore, the first book happens 1991. We know Harry’s birthday thanks to a Daily Prophet article in Sorcerer’s Stone that states the break-in at wizarding bank Gringotts occurred on July 31, with Harry responding, “That Gringotts break-in happened on my birthday!”

All of that means there were exactly nine and three-quarter years between Voldemort’s attack on Harry on Oct. 31, 1981, and Harry finding out he was a wizard on his 11th birthday on July 31, 1991. Mind blown!

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