There were no witnesses, except for Harry, who was still a baby and didn't relive / remember the experience until much later. James and Lily were both dead, Voldemort was not quite dead but not much better and not likely to tell anyone what happened.

So how did Dumbledore, or anyone, know that Lily sacrificed herself for Harry?

Keep in mind that even finding out what happened in a more general sense, that James and Lily had died and Voldemort had been killed by a rebounding killing curse, was difficult enough.

Of course, it would be clear they had died defending their family, themselves and Harry, but nothing found at the scene would have told anyone that Lily had been given the choice to live, but did not take it. Perhaps James had been given the same choice, but declined as well. Or — less likely — perhaps he was the only one given the choice, while Lily was killed right away.

Yet Dumbledore seems to have known, as shown in this quote (emphasis mine):

But I knew, too, where Voldemort was weak. And so I made my decision. You would be protected by an ancient magic of which he knows, which he despises, and which he has always, therefore, underestimated — to his cost. I am speaking, of course, of the fact that your mother died to save you. She gave you a lingering protection he never expected, a protection that flows in your veins to this day. I put my trust, therefore, in your mother’s blood. I delivered you to her sister, her only remaining relative.

She may have taken you grudgingly, furiously, unwillingly, bitterly, yet still she took you, and in doing so, she sealed the charm I placed upon you. Your mother’s sacrifice made the bond of blood the strongest shield I could give you.

Order of the Phoenix, Chapter 37. Thanks to Anthony Grist for pointing out.

Here, Dumbledore talks about Lily's sacrifice, specifically her sacrifice, not just dying defending him, like what happened to James. Since Harry is delivered to the Dursleys within 24 hours, Dumbledore must have found out within that time span. And he must have known with enough confidence to base the entire protection of Harry upon that fact.

Of course, he must have known about this kind of magic, as the quote shows. But how did he know it was applicable to Lily and Harry?

This question has been asked on Quora, however, I can't read beyond the first answer there and even if I signed up to read all answers, from what I've heard, Quora doesn't seem to be the most reliable source.

Slytherincess pointed me to a related question of hers, in which she asks how Voldemort knew about this type of magic (JKR's books and interviews seem to contradict each other there). But what I want to know is how it was found out what happened, with such detail that Dumbledore knew Lily had sacrificed herself.

  • 53
    is "magic" an answer?
    – calccrypto
    Commented Jun 18, 2014 at 8:05
  • 8
    Related interview: the-leaky-cauldron.org/2007/12/23/… “How did Dumbledore find out about what happened in Godric's Hollow?” JKR’s answer is a bit of a fluff, and doesn’t really tackle this question specifically, but might be interesting anyway. (via the Quora thread)
    – alexwlchan
    Commented Jun 18, 2014 at 12:49
  • 6
    I have always assumed that Voldemort's wand would have been left at the scene as he departed his body when the killing curse aimed at Harry rebounded. The Priori Incantatem spell would allow for some deduction of events.. though this is purely speculative as Voldemort had his own wand back when he was resurrected in the cemetery by Wormtail.
    – Ian Lewis
    Commented Jun 18, 2014 at 14:42
  • 2
    @IanLewis I think Wormtail retrieved the wand, so no chance for Priori Incantatem spells. although, that could be a whole other question, why did no one bother to retrieve his wand and snap it? scifi.stackexchange.com/questions/4493/…
    – BP_Phoenix
    Commented Jun 18, 2014 at 15:30
  • 6
    Maybe I misunderstood the way it all went down that night, but wouldn't Harry's scar have been a big clue? Dumbledore could have seen that scar, known what kind of act would have produced it, seen two dead parents and an absent Voldemort, and deduced without much difficulty what happened, right?
    – Nerrolken
    Commented Oct 23, 2014 at 22:53

16 Answers 16


Dumbledore could have visited the place shortly after the fall of Voldemort and replayed the scene using Appare Vestigium

Although there is another post that tried to answer the "or anyone"-part of the question using new material from Harry Potter and the Cursed Child, it didn't answer on how Dumbledore himself found out what happened. With the release of the recent "The Crimes of Grindelwald" movie, we might finally have an answer.

In the movie, we can see Newt, while searching for Porpentina, cast a previously unknown tracing spell. This spell seems to reveal and illuminate traces of recent magic, with some sort of "gold dust" that sits on top of things that were constituting the scenery, even if these items are gone when the spell is incarnated.

Newt casting Appare Vestigium

Although it is Newt that casts the spell and not Dumbledore, the existence of it proves that there is a canon way of finding out what happened in terms of magic at a specific place, hours after the events unfolded.

Dumbledore replaying the scene in such detail could reveal to him that Voldemort threatened to kill Lilly, offered her a choice to flee, and cast Avada Kedavra on her, as well as his ultimate attempt to kill Harry. Then, he would witness the curse that rebounded on him, the destruction of his body etc. Putting 2 and 2 together would make him infer that Harry was saved due to his mother's apparent self-sacrifice, something that proved to be vital information in the entire series.

Note: The fact that magic leaves traces behind, is stated by none other than Dumbledore himself:

“Magic always leaves traces,” said Dumbledore, as the boat hit the bank with a gentle bump, “sometimes very distinctive traces. I taught Tom Riddle. I know his style.”

Harry Potter and the Half-Blood Prince, Chapter 26 "The Cave" [Emphasis mine]

  • Was this spell done on-site?
    – Alex
    Commented Mar 25, 2019 at 17:10
  • Yes, it was cast in the exact location where the previous night Porpentina, Credence and Nagini were. Commented Mar 25, 2019 at 17:13
  • So that would probably mean that Dumbledore would have had to go to Godric's Hollow to do it.
    – Alex
    Commented Mar 25, 2019 at 17:13
  • 1
    Yes, that's what I implied above. We know that Hagrid went there to retrieve Harry-baby and JK Rowling had stated that he probably had placed an alarm spell to inform him if an attack happened. So, he would know when it happened and we can theorize that he could have visited shortly after Hagrid left the place. Commented Mar 25, 2019 at 17:15
  • 1
    Perhaps a bit of a stretch...
    – Alex
    Commented Mar 25, 2019 at 17:27

I think the answer is likely a combination of everybody's favourite Potions master, Severus Snape, and some solid guesswork on Dumbledore's part. Dumbledore knew even before their deaths that Snape had asked Voldemort to spare Lily's life:

“If she means so much to you,” said Dumbledore, “surely Lord Voldemort will spare her? Could you not ask for mercy for the mother, in exchange for the son?”

“I have — I have asked him —”


The hilltop faded, and Harry stood in Dumbledore’s office, and something was making a terrible sound, like a wounded animal. Snape was slumped forward in a chair and Dumbledore was standing over him, looking grim. After a moment or two, Snape raised his face, and he looked like a man who had lived a hundred years of misery since leaving the wild hilltop.

“I thought … you were going … to keep her … safe. …”

“She and James put their faith in the wrong person,” said Dumbledore. “Rather like you, Severus. Weren’t you hoping that Lord Voldemort would spare her?”
Harry Potter and the Deathly Hallows, Chapter 33 - The Prince's Tale

Clearly they believed, for whatever reason, that Voldemort would keep his word. From there it's not a big leap to conclude that, since she had also been killed, she'd refused his offer to save herself.

As SQB stated in the comments, this all hinges on Dumbledore and Snape's belief that Voldemort would keep his word. Why would they do so?

At its simplest, Voldemort has absolutely no reason not to keep his word. Snape had helped him tremendously by informing him of (part of) the prophecy, and - as Voldemort said to Wormtail after his resurrection in Goblet of Fire - Voldemort rewards his helpers. Harry was the only thing he viewed as a threat, the last thing standing between him and true immortality, so keeping Lily alive doesn't impact him at all.

By keeping her alive he would secure Snape's allegiance by giving him the one thing he desires above all else. He may even have hoped that, given enough time, Lily could be persuaded to join him. He seems sufficiently lacking in understanding of human emotions to have considered that possibility; obviously she's never actually going to love the man who gave up her husband and son to be murdered, or join with the one who murdered them.

  • 11
    @zyboxinternational Dumbledore built the protection on Harry at the Dursleys on top of Lily's sacrificial protection, so he obviously knew about it roughly a decade before Voldemort told Harry at the end of the first book. Commented Jun 18, 2014 at 20:15
  • 14
    @zyboxinternational “But I knew, too, where Voldemort was weak. And so I made my decision. You would be protected by an ancient magic of which he knows, which he despises, and which he has always, therefore, underestimated - to his cost. I am speaking, of course, of the fact that your mother died to save you. She gave you a lingering protection he never expected, a protection that flows in your veins to this day. I put my trust, therefore, in your mother’s blood. I delivered you to her sister, her only remaining relative.” Commented Jun 18, 2014 at 20:31
  • 14
    “She may have taken you grudgingly, furiously, unwillingly, bitterly, yet still she took you, and in doing so, she sealed the charm I placed upon you. Your mother’s sacrifice made the bond of blood the strongest shield I could give you.” (Order of the Phoenix, Chapter 37). He obviously knew about Lily's sacrifice when he placed Harry with the Dursleys, so he didn't find out at the end of the first book when Harry was eleven. Commented Jun 18, 2014 at 20:32
  • 1
    Interesting, but then as I said before, it could easily be a result of Dumbledore's guesswork. Remember that much of Dumbledore's guesswork turned out to be correct, after all, it took Dumbledore a decade or so to confirm his suspicion about Voldemort's horcruxes, and only did so when Harry & Ginny became a victim of one.
    – AStopher
    Commented Jun 18, 2014 at 20:32
  • 1
    Your answer hinges on Snape's and Dumbledore's belief in Voldemort keeping his word. Why would they trust him to do so?
    – SQB
    Commented Jun 19, 2014 at 8:46

There is no reason why the Pensieve would not work on an infant. Harry could see and hear what was happening, even if he couldn't understand it.

So Dumbledore could have watched the whole thing from Harry's point of view and learned exactly what happened.

(One could argue that a baby's vision and memory are not fully developed, but the magic of the Pensieve might be able to overcome that. Frankly if you are going to talk about scientifically implausible events in Harry Potter this would be a long way down the list.)

  • 14
    I don’t have a quote to hand, but I’m fairly sure JKR has said that a Pensieve replays events as they actually happened, not as they were remembered.
    – alexwlchan
    Commented Jun 18, 2014 at 8:26
  • 3
    @alexwlchan That seems likely. Harry was able to look around independently while inside the Penseive in Goblet of Fire, he didn't see only what Dumbledore saw. He was also able to walk away from Snape a certain distance and listen to conversations between the Marauders that Snape likely didn't hear himself. Commented Jun 18, 2014 at 12:18
  • 2
    Here's the quote. accio-quote.org/articles/2005/0705-tlc_mugglenet-anelli-3.htm “Do the memories stored in a Pensieve reflect reality or the views of the person they belong to?”
    – alexwlchan
    Commented Jun 18, 2014 at 12:21
  • 14
    Can't be, because Dumbledore didn't see Harry until after he knew. In the Sorcerer's Stone Hagrid says he pulled Harry from the wrecked house. There wasn't a chance for him to extract the memory and view it.
    – MAW74656
    Commented Jun 18, 2014 at 14:54
  • 4
    Also, doesn't someone have to give a memory for it be viewed in a Pensieve. I can't imagine infant Harry being able to do such a thing
    – chama
    Commented Jun 20, 2014 at 14:28

For a Pottercast interview in 2007, JK Rowling addresses this question in part (edited for clarity):

SU: How did Dumbledore find out about what happened in Godric's Hollow?

MA: And what happened? There's this whole twenty four hours that people have been fantasising about for years.

JKR: Obviously Dumbledore could cast a spell on a dwelling that would immediately alert him if something happened to it. (SU: Oh.) So he could know instantaneously. That's not a problem at all. And then he could dispatch Hagrid and so on.

She doesn’t go into details about what this spell entails, but I think it was probably a significant factor. I think it certainly would have told him that Voldemort had attacked the house, and probably that somebody had survived (using a remote variant of Homenum Revelio).

Personally I think this spell was akin to an aircraft flight recorder, or a “black box”. It was recording events at the house (audio would probably be sufficient, but it probably also monitored magic within the house), and it alerted Dumbledore when Voldemort arrived. He was able to playback the recording after the fact, and used his considerable knowledge to deduce what happened.

This means he would have known what had happened (and what to do next) almost immediately, which is consistent with the canon. It’s only a guess, but it’s the best I’ve got.

I also briefly considered legilimency and/or use of Harry’s memories in the Pensieve. I discarded this theory on two grounds:

  1. It’s inconsistent with the sequence of events. If Hagrid and Dumbledore’s reports are accurate, then the first time Dumbledore sees Harry after the attack is when Hagrid brings him to Little Whinging. This means there's no opportunity for Dumbledore to inspect his memories, and thus no reason for him to bring them to the Dursleys.

  2. It’s potentially traumatising for Harry. The use of legilimency we see in Half-Blood Prince sees Harry reliving the memories that Snape’s inspecting. Even if Dumbledore could inspect Harry’s memories before taking him to the Dursleys, I think there’s a risk of further damage if he’s forced to relive his parents’ death just hours after it happened. I don’t think Dumbledore would want to risk it.

(Out-of-universe) The full transcript of the interview above points to @SQB’s theory as the correct one: that J.K. Rowling got this one wrong. That doesn’t mean there isn’t an in-universe explanation, or that there isn’t an explanation consistent with the existing canon, but it is worth noting.

MA: And what happened? There's this whole twenty four hours that people have been fantasizing about for years.

JKR: Yeah, I know. I've got a bit of problem with this myself, because every time I think it straight in my head I go back and look at what the fans are theorizing about, and I think "Yeah, maybe they've got a point." Dumbledore – Well there's an easy answer to how would Dumbledore know. Because you can – He? (laughs) You can. One can.

MA: Yeah. Yeah. (SU laughs)

JKR: Forgive me if I speak as though it's all real for a moment. (clears her throat)

SU: It is real! What do you mean it's not?

JN: That's what we all feel.

JKR: I know, exactly! That's how I feel as well. Yeah, so okay. Obviously Dumbledore could cast a spell on a dwelling that would immediately alert him if something happened to it. (SU: Oh.) So he could know instantaneously. That's not a problem at all. And then he could dispatch Hagrid and so on. I think The Scottish Book will have to answer that question. (SU, MA, and JN laugh) I'm gonna have to really go back through notes and either admit that I lost twenty four hours or I don't know, hurriedly come up with some back story to fill in. (SU laughs) Either way, you either get to be right, or you get more story. So you can't complain.

  • 2
    Good point about the memories: Dumbledore could have extracted the memory from Harry, but not until Privet Drive—and by that time, as you say, he must already have known about the sacrifice in order to be able to decide to use Lily’s protection as the strengthening basis of his own protective charms on Harry living with his blood relative. Commented May 18, 2015 at 10:07
  • 3
    i think this is probably the best answer, though i think something similar to the ministries trace is what was cast on the house, which records the exact spells being cast, this would show that he cast X killing curses, and potentially even show lilys use of protective magic, as the trace was able to read harrys wandless magic in book 3 on his aunt marge, as well as dobbys use of wandless hoving charm from book 2. It seems Very accurate. the ministry would also have had this info via the trace on harry(unless the trace starts later in life)
    – Himarm
    Commented Oct 9, 2015 at 15:28

"You all know that on the night I lost my powers and my body, I tried to kill him. His mother died in the attempt to save him - and unwittingly provided him with a protection I admit I had not foreseen. ... I could not touch the boy."


"His mother left upon him the traces other sacrifice. This is old magic, I should have remembered it, I was foolish to overlook it. but no matter. I can touch him now."

Harry Potter and the Goblet of Fire Pg.421

We have traces from around the entire story that Voldemort is known to overlook things. Specially, at that time, he was over-confident about his powers.

They, who had seen proofs of the immensity of my power in the times when I was mightier than any wizard living?

Harry Potter and the Goblet of Fire Pg.421

He lived with a false interpretation that no one is more clever than him. That's why he said:

I knew wizards everywhere would one day fear to speak, when I had become the greatest sorcerer in the world!

Harry Potter and the Chamber of Secrets Pg.314

Dumbledore on the other hand is careful enough to admire every aspect of the situation and then come to a decision. He is pretty clever in real. If Voldemort could know that it is an old magic, then why not Dumbledore?

Not to mention, Dumbledore did not instantly come to a decision. It took him time. One of the first appearances of his possible clues were in the first book:

"But why couldn't Quirrell touch me?"

"Your mother died to save you. If there is one thing Voldemort cannot understand, it is love. He didn't realize that love as powerful as your mother's for you leaves its own mark. Not a scar, no visible sign... to have been loved so deeply, even though the person who loved us is gone, will give us some protection forever. It is in your very skin.

Harry Potter and the Philosopher's Stone Pg.241

So, I guess. This must be a magic, popularity of which is similar to that of a Horcrux. It wasn't something very much unknown, but it was known only to those who had gone deep into the studies of magic. Dumbledore and Voldemort, both qualify to this category, only difference is Voldemort is ignorant, foolish, idiot and over-confident (and evil of course).

It won't be extremely difficult for him to know this. There were other clues as well. See Anthony Grist's answer.

If Dumbledore can work out the location of a Horcrux heavily armed from traces of magic, this isn't difficult.

“And you knew this? You knew—all along?”

I guessed. But my guesses have usually been good,” said Dumbledore happily, and they sat in silence for what seemed like a long time, while the creature behind them continued to whimper and tremble.

Harry Potter and the Deathly Hallows Pg.593

  • 1
    Also, your last quote is exactly what my question is. How does Dumbledore know this?
    – SQB
    Commented Jun 18, 2014 at 17:21
  • @SQB The part before the last quote is to justify how does Dumbledore know this :P Commented Jun 18, 2014 at 17:22
  • This! I think this is the correct answer. Also, it is rather commonly known that Avada Kedavra has no counter spell. Anyone would be sure that Voldemort must have used the killing curse (after all, this was his mission's objective). Dumbledore would have put two and two together and understood the only means of stopping the killing curse is sacrificial protection. Commented Oct 26, 2017 at 8:53
  • 1
    I'm not sure this really answers the question. The majority of the post only discusses Dumbledore's ability to know of the concept of such protection, but the question was how he knew that such protection was implemented in this specific case. The rest of the post just says that if Dumbledore was able to figure out other things it wouldn't be difficult for him to figure this out, but that also doesn't address how he figured it out in this particular case.
    – Alex
    Commented Mar 5, 2019 at 0:27

If Lily hadn't sacrificed herself for Harry's life then even Harry would have been dead.

Since Harry was not dead & Voldemort was sort of dead, it would be easy for a mind like Dumbledore's to deduce that Lily used the magic of love & sacrifice to protect Harry. No other magic could deflect Avada Kedavra.

  • 12
    Even though the power of Lily's love is a reasonable theory, there doesn't seem to be any conclusive evidence that it was the case. Frankly, Dumbledore could have concluded anything else: maybe Harry has anti-magic skin, or maybe Voldemort's wand was broken and killed himself, etc etc.
    – Saturn
    Commented Jun 18, 2014 at 7:55
  • 7
    Still not conclusive.
    – Saturn
    Commented Jun 18, 2014 at 8:23
  • 18
    @Voldemort: You're just bitter because you were defeated by a baby. :-) Commented Jun 18, 2014 at 8:24
  • 7
    @KharoBangdo: That was an example. The point is that it could have been anything else, since there were no witnesses.
    – Saturn
    Commented Jun 18, 2014 at 8:34
  • 9
    @Voldemort you mean "(...) maybe my wand was broken (...)"?
    – SQB
    Commented Jun 18, 2014 at 8:47

I knew there must be a reason why I didn't answer this question right away! New canon -- who would have thought? Anyhow, spoilers for Harry Potter and the Cursed Child, published 07.30.16, and deemed as bona fide canon by J.K. Rowling:

Delphi Diggory (Voldemort's secret daughter by Bellatrix Lestrange) and Voldemort himself at the very least knew that Lily sacrificed herself in the name of love for Harry:

DELPHI: Your mission is a mistake. Attacking Harry Potter is a mistake. He will destroy you.

HARRY/VOLDEMORT's hand turns into HARRY's hand. He looks at it, astonished and dismayed, and then quickly pulls it inside his sleeve.

HARRY/VOLDEMORT: He is a baby.

DELPHI: He has his mother's love. Your spell will rebound, destroying you and making him too powerful and you too weak. You will recover to spend the next seventeen years consumed in a battle with him -- a battle you will lose.

HARRY/VOLDEMORT's hair begins to sprout, he feels it, he attempts to cover it. He pulls his hood over his head.

HARRY/VOLDEMORT: Then I will not attack him.

Harry Potter and the Cursed Child - Part Two, Act Four, Scene Eleven, Godric's Hollow, St. Jerome's Church, 1981 - Page 285 - Scholastic


Delphi Diggory knew of Trelawney's prophecy and of Harry and Voldemort's story, and also how Lily sacrificed her own life out of her tremendous love for Harry, because Delphi was from the future. She learned all the information regarding Voldemort, and subsequently Harry, through her intense need to know everything possible about her father, Voldemort. Prior to Delphi being intercepted by time-travelling Harry et al at St Jerome's Church in Godric's Hollow on Halloween 1981, Delphi was the only person who for certain knew of 1) Trelawney's full prophecy, 2) that Voldemort's curse would rebound, and 3) that the reason Voldemort's curse rebounds would be sacrificial love on Lily's part.

As far as Dumbledore goes, he had the clue of the prophecy since the day he interviewed Professor Trelawney at the Hog's Head pub; I can't find anywhere specifically in canon that indicates exactly how Dumbledore put two and two together and tied Lily's love for Harry to Voldemort's failure to kill him. I think it's fair to say that Dumbledore, a brilliant man, rightly concluded the power that saved Harry was love over a period of intense deduction. It's hard to pinpoint; J.K. Rowling herself has spoken to this in an interview, and outright said the ancient magic Lily invoked was without precedent -- it had never happened before. Based on this point, it would seem there would be no one else who should have known about Lily's sacrificial magic.

  • 2
    Harry outlines everything Delphi new in the last fight with voldemort so it was probably public information for her growing up.
    – Himarm
    Commented Aug 11, 2016 at 14:29
  • 4
    It was public information after Voldemort died in the Battle of Hogwarts, of course. But it was not public information on Halloween of 1981, the day Voldemort attacked and tried to kill Harry -- no one knew. That type of magic had never happened before (per JKR interview). A person would have to obtain the info from the future if they were to possess it on the night Lily died and Voldemort lost his powers. If there is another explanation, I'm totally open to being convinced of it. Look, I'm not fond of the new canon, but it is what it is, and I think this answer reflects that. Commented Aug 13, 2016 at 23:34
  • 3
    @slytherincess So are you saying that Delphi, and the crew who went back in time and met at Godric's Hollow, told someone else, while in the past? You didn't assert that, but you must be implying it... But there is no proof of that, either. If the people from the future went to the past, did whatever they did, and went back to the future with no one in the past knowing, then no one in the past gained "future information", right? Commented Sep 6, 2016 at 20:17
  • 27
    Harry Potter and the Cursed Child is not canon! Commented Oct 9, 2016 at 10:50

Here's a logical argument for how Dumbledore could have worked out what happened beyond all reasonable doubt.

  1. The Killing Curse was cast both at Lily and Harry. In Lily's case, this could probably be deduced from the condition of her body: Avada Kedavra leaves no traces on the body, unlike any other form of murder (which is why the Muggle authorities were so confused by the deaths of Tom Riddle Sr. and his parents). Both cases are also covered by Dumbledore's ability to detect traces of magic, as discussed in How did Dumbledore detect the "traces of magic" in the Cave?, and to differentiate between different types of magic - in the same scene in the cave, he is able to tell that blood is required for them to pass through the rocks. (See also the answer to How did anyone know the Unforgivable Curse was used on baby Harry Potter?.)

  2. Harry survived the Killing Curse. He is the only person ever known to have done so, as we know from Barty Crouch Jr. / Alastor Moody:

    "Not pleasant. And there's no countercurse. There's no blocking it. Only one known person has ever survived it, and he's sitting right in front of me."

  3. There is only one way to survive the Killing Curse (probably). Since surviving it only ever happened that one time, there's surely only that one way anyone can survive it. And Dumbledore almost certainly knew of this protective magic, since even Voldemort did:

    "His mother left upon him the traces of her sacrifice. This is old magic, I should have remembered it, I was foolish to overlook it."

    What Voldemort perhaps had not realised, but Dumbledore would, was that this protective magic (of which Voldemort did know) would be powerful enough even to repel the Killing Curse. At this stage, we've got as far as deducing that someone sacrificed themselves in order for Harry to survive.

  4. Lily was the one who sacrificed herself. Firstly, she was found beside Harry, while James was killed much further from him; it was clear that she was the last line of defence against Voldemort. Secondly, if it had been James who'd sacrificed himself, he would likely have done so with the intent of protecting both his wife and son, and Voldemort wouldn't have been able to kill Lily either.

The conclusion is that Lily, by performing the ultimate sacrifice, cast a powerful protective spell over Harry. Dumbledore was old, clever, and knowledgeable enough to come to this conclusion - no other possibility would fit - and he based his plan of protecting Harry over the next 15 years on this.

  • I like your interpretation because it does not rely on the slightly sexist idea that only a MOTHER's love is magical.
    – Pwassonne
    Commented Apr 20, 2016 at 18:26
  • 1
    @Pwassonne - I hate to be the party pooper, but JKR has said she does feel there is a special bond between a mother and her child -- a bond so precious that she wrote a whole series based around its premise. That said, she doesn't say a father's love absolutely cannot elicit the same magical force as did Lily's love; James wasn't given a choice whether to die for Harry or save himself. He was just executed right out of the gate. :) Commented Aug 13, 2016 at 23:43
  • @Slytherincess I guess as long as she didn't say it would never have been possible with a father's love, it's fine with me...
    – Pwassonne
    Commented Aug 18, 2016 at 15:46
  • 1
    Let's add one more point: After deducing the above, Dumbledore puts his hypothesis to a test, and casts the magic that ties Lily's sacrifice to the Dursley residence so that Harry will be protected there. Then, when Petunia takes Harry in, Dumbledore is able to detect that the spell has taken effect. This confirms that Lily was indeed the one who sacrificed herself.
    – EvilSnack
    Commented Dec 4, 2018 at 4:46

Let's try to break this down. What are the known facts?


  1. Voldemort kills James and Lily, and attempts to kill Harry.

  2. Doubledore does not see Harry until Hagrid arrives in front of the Dursley's.

  3. Dumbledore knew of the attack via the quote Alex found from JKR.

    JKR: Obviously Dumbledore could cast a spell on a dwelling that would immediately alert him if something happened to it. So he could know instantaneously. That's not a problem at all. And then he could dispatch Hagrid and so on.

  4. Dumbledore has already written the letter to Petunia before ever seeing Harry.

  5. Very few things can stop/reflect a killing curse, via Jeff's answer.

What is safe to assume Dumbledore knows (although he hasn't seen any of this first hand):

  1. The house is destroyed.

  2. Obviously, Harry is alive.

  3. Voldemort appears to have died/vanished.

  4. Voldemort claimed to Snape that he would spare Lily, but Lily is dead, meaning Voldemort lied — not unheard of — or Lily interfered.

What Dumbledore probably knew:

  1. Voldemort's lack of understanding/disregard of sacrificial/love, and deep, ancient magic.

  2. What parents are willing to do for their children, (aka what Dumbledore's own father did in revenge for the torture of his daughter)

  3. That both Lily and James would be willing die to save Harry.

  4. That something blocked/reflected the killing curse, causing an explosion. (This is based on the fact that a killing curse causes an explosion hitting non-living objects. For example, the statues in the fight between Dumbledore and Voldy in the Ministry.)

Side info useful for our conclusions:

  1. The Ministry of Magic uses the Trace on all under-aged wizards.

  2. The Trace is able to tell what magic is being cast in the vicinity of the Trace holder.

  3. The Trace is not distinct enough to tell who cast the spell.

  4. The Trace does know which spells are cast.

  5. The Trace can even detect wandless magic, and accurately tell what spell was cast. (Examples: Dobby's hovering charm and Harry enlarging his aunt).

  6. (Speculatively) We know that Dumbledore either himself, or via an ally, has knowledge of underage magic — at least with Harry — specifically within seconds of it happening. From book 5, Harry getting expelled, to the revision to a hearing, within minutes.

Things we know didn't happen:

  1. Dumbledore used the Pensieve on Harry to see his memories.

This leads us to some possible scenarios:

  1. Dumbledore's spell that was cast on the Potter's dwelling was similar to the Trace, in that it recorded the magic being used in the house. This would allow him to know for sure that killing curses were cast, as well as potentially even informing him about the magic released from Lily's sacrifice. If that is the case he could have known for sure what happened, and so knew to finish the protective spell cast by Lily's death was to take Harry to Petunia.

  2. Dumbledore pieced together what he heard from the various secondhand accounts, and made one of his mental leaps that he does so well, and accurately. As we see throughout the series, the only thing that would have deflected the killing curse, would have been the ancient form of magic specifically that Lily used. Nothing else could have adequately explained how a killing curse failed to kill someone.

  3. Dumbledore was able to check the Trace logs on Harry himself via the Ministry to see what spells had been cast in Harry's immediate area that night.

TL;DR / Final Conclusion

Dumbledore is highly intelligent. Over and over again we've seen how, with limited info, Dumbledore is able to intuitively leap to a correct, or mostly correct conclusion. That said, he had a lot of info to work with that night. He knows that the Potters died — JKR told us he had the house essentially bugged — so he knew specifically that Voldemort had attacked their house. He knows Harry is alive, so something deflected Voldemort's killing curse, potentially rebounding onto Voldemort, and blowing up half of the upstairs of the house. He knows that Voldemort is vulnerable to old, ancient, love-based magic. He knows that Lily and James will die for Harry. Adding all these things up, knowing he himself is aware of and studies said old, ancient, love-based magic, would lead us to conclude that unless there are multiple old spells, it was the only known form of sacrificial protective magic that spared Harry, which prompts Dumbledore to immediately write a letter, and set Hagrid to bring Harry to the Dursleys, which would complete the spell.

My opinion, based on what we know, is that the spell monitoring the Potters' house was similar, if not the same, magic as is used in the Trace itself, which would have further proved and made absolute in his mind what form of protective magic Lily's sacrifice granted Harry.



"This is old magic, I should have remembered it, I was foolish to overlook it"

Voldemort clearly knew about it, even if he didn't think about it as a threat. Is it a huge leap to assume that Dumbledore did too?

Especially considering it's strongly implied that Voldemort only forgot it because he thought he was all-powerful? In that moment, had no reason to assume a baby could be any threat, so wasn't analysing the situation and thinking about risks, therefore didn't think about the "Old magic"

Dumbledore, with a few moments to think and an unclouded mind, not to mention being "closer" to the concepts of love and protection (concepts alien to Voldemort) would surely have been able to recall it? He's also keenly intelligent and has a huge knowledge of magic even before the events surrounding Harry's death (he was already "the only wizard Voldemort was afraid of")

With this knowledge and a few moments with the crime scene (priori incantatem, for a start, showing that Voldemort killed Lily a moment before) I really can't see how this would be beyond Dumbledore to work out.

  • A good answer, but the part with V remembering the 'Old Magic' has been mentioned.
    – Möoz
    Commented Oct 23, 2014 at 22:37
  • Indeed, but not discussed in quite the same context.
    – Jon Story
    Commented Oct 23, 2014 at 22:38
  • Thank you for your answer. However, I'd like to point out that Dumbledore probably hadn't been at the crime scene at that time. So while Dumbledore must have known about that kind of magic (as the quote in my question shows), my question is how did he know it was applicable in this case?
    – SQB
    Commented Oct 24, 2014 at 7:08
  • He wasn't there immediately, but look at Dumbledore at the Horcrux cave - without performing a single spell, he works out how to open Voldemort's secret door and finds the exact spot to open it. The way Dumbledore talks about the Love thing early in the first couple of books, too, shows that Dumbledore wasn't 100% sure about the Love connection: he just strongly suspects it and can't prove any other reason. I stick with "He didn't know it wasn't applicable in this case, but he worked it out" - in short, then, he used reason and the facts available to find the most likely answer.
    – Jon Story
    Commented Jun 8, 2015 at 13:12
  • And as he admits before he dies, he's not infallible: he makes mistakes. He didn't know at all, he just had his best guess with the information he had. The same way any of us really "know" anything
    – Jon Story
    Commented Jun 8, 2015 at 13:12

First of all, let's consider the following facts:

  • Avada Kedavra has no counter-curse or blocking spell
  • Harry Potter was a year and a couple months old
  • Lily was found dead in the same room where Harry was found
  • Dumbledore knew Sybill Trelawney's prophecy

Now, the quotes (all emphasis mine):

  1. The prophecy:

    "The one with the power to vanquish the Dark Lord approaches... born to those who have thrice defied him, born as the seventh month dies... and the Dark Lord will mark him as his equal, but he will have power the Dark Lord knows not... and either must die at the hand of the other for neither can live while the other survives... the one with the power to vanquish the Dark Lord will be born as the seventh month dies...."

  2. Dumbledore to Harry, after the confrontation with Quirrell / Head Voldemort:

    Your mother died to save you. If there is one thing Voldemort cannot understand, it is love. He didn't realize that love as powerful as your mother's for you leaves its own mark. Not a scar, no visible sign ... to have been loved so deeply, even though the person who loved us is gone, will give us some protection forever.

  3. Slughorn about Amortentia:

    "Amortentia doesn't really create love, of course. It is impossible to manufacture or imitate love. No, this will simply cause a powerful infatuation or obsession. It is probably the most dangerous and powerful potion in this room -- oh yes," he said, nodding gravely at Malfoy and Nott, both of whom were smirking skeptically. "When you have seen as much of life as I have, you will not underestimate the power of obsessive love."

  4. A VERY IMPORTANT memory from the pensieve:

    "I have pushed the boundaries of magic further, perhaps, than they have ever been pushed --" "Of some kinds of magic," Dumbledore corrected him quietly. "Of some. Of others, you remain...forgive me...woefully ignorant." For the first time, Voldemort smiled. It was a taut leer, an evil thing, more threatening than a look of rage. "The old argument," he said softly. "But nothing I have seen in the world has supported your famous pronouncements that love is more powerful than my kind of magic, Dumbledore." "Perhaps you have been looking in the wrong places," suggested Dumbledore."

  5. Dumbledore on the way Voldemort was conceived:

    "Personally, I am inclined to think that she used a love potion. I am sure it would have seemed more romantic to her."

On October 31, 1981, a prophecy made sometime earlier in the year of 1980 began to come true. When Voldemort was "defeated", or merely temporarily "killed", by Harry, many questions were answered, and many surfaced from the events of the night.

  • Is Harry the Chosen One? Yes.

  • Will one of them kill the other? Yes.

  • What is the power Harry has and Voldemort does not? How did Harry survive?

    Which brings us to your question. My first, second, third, and fourth quotes provide proof of what Dumbledore knew to be fact.

  • Amortentia does not create love.

  • Voldemort does not know the power of love, as is made clear in the fourth quote.

  • There is a power Harry will have that Voldemort does not know nor understand (in other words, a power Voldemort is ignorant to).

Dumbledore knew Voldemort does not know love (and was guessing this was because of Amortentia, but this guess is not essential for the conclusion, only supports it), knew there was no counter-curse, knew of the protection spell, and knew Harry's mother died with him. On top of everything, Dumbledore is a very old wizard who has seen it all.

P.s. it never actually says Dumbledore knew for sure that was the way Harry survived. Dumbledore only tells Harry about the protection spell after the Quirrel/Head Voldemort confrontation, and by then it was super obvious by the fact that Quirrell couldn't touch Harry. And the fact the he sent Harry to the Dursley's? He could have been acting on suspicion, plus in Harry Potter and the Half Blood Prince, Dumbledore tells the Dursleys he believed they were going to treat Harry like a son when he dropped him off as a baby. He had no way of knowing they were terrible people, and Harry would have most likely ended up with them even if Dumbledore wasn't thinking about the protection spell, being his only family and such.


I was curious about this myself. Now we're getting new canon (I consider Fantastic Beasts movies to be canon) and new information on the magical world.

In Fantastic Beasts: The Crimes of Grindelwald we are introduced to a new spell that can explain how Dumbledore could know the details of what happened in Godric's Hallow.

I got the information from the answer on (SPOILER ALERT) this question so all credits to @Valorum

In the movie we see Newt cast Appare Vestigium spell that allows you to trace resent magic activity in an area. The way it is shown in the movie it is extremely useful tool to actually see the events with your own eyes - almost as if you were there.

I think it is safe to assume Dumbledore can perform the spell. Though it looks like he didn't go personally to Godric's Hallow after the Potters were killed, we can't be sure of that. He could send Hagrid to pick up the baby while being busy with some other issues, but as there are full 24 hours between the murder and him meeting Hagrid at Privet Drive, he could easily pop in to investigate the place sometimes within these hours.


Voldemort himself told Harry, in the Philosopher's Stone (Sorcerer's Stone to you American folk).

A small extract from page 213 in the chapter "The Man with Two Faces":

'How touching ...' it hissed. 'I always value bravery ... Yes, boy, your parents were brave ... I killed your father first and he put up a courageous fight ... but your mother needn't have died ... she was trying to protect you ...'

Nowhere previously in the book does it say this, and to expand on Awal Garg's quote from his answer:

"But why couldn't Quirrell touch me?"

"Your mother died to save you. If there is one thing Voldemort cannot understand, it is love. He didn't realize that love as powerful as your mother's for you leaves its own mark. Not a scar, no visible sign... to have been loved so deeply, even though the person who loved us is gone, will give us some protection forever. It is in your very skin.

In the paragraph prior to this one (in the book- page 216):

'Well ... Voldemort said that he only killed my mother because she tried to stop him killing me.'

Harry recalls to Dumbledore what Voldemort had told Harry about Lily dying to protect Harry, therefore we can conclude that Lily sacrificed herself for Harry.


Well, quite apart from magical means or information from Snape, there's also the physical evidence: Lily's body is in front of Harry, protecting him. Possibly, the position Voldemort's body (if it still exists) and wand indicate that he tried to attack Harry.

Of course, Priori Incantatem would also give evidence, as well as the fact that both Dumbledore and Snape knew that Voldemort had promised to spare Lily if she did not interfere.


The bodies placed in the house in such a way suggested that lily died after james. which would mean either she was shielding him directly while hugging him or she was blocking voldemorts view to harry in the bedroom. both scenarios show she was shielding harry which started all the ancient spell. But we must also remember that both parents died saving harry. So even if james was not shielding him literally like lily, he was still protecting him.

The main point being, this ancient spell was stronger when it continued protection by a blood relative. But James' direct family are all dead. aren't they? also the extended family would all be magical and we dont know who is in voldemort's pocket. So the last living immediate relative was petunia.

A mother wouldn't leave her child even to go fight in such a situation when the father is available to do so.

btw somebody gave a similar answer but was downvoted....

breaking it down, yes both parents sacrifised, but lily was doing it literally which had a powerful imagery generally adding power to ancient spells which was unwittingly started by her started because ofcourse nobody expected it in the first place. It is just safe to assume that even if dumbledore was wrong, since both lily and james died, petunia was the only choice as reasoned above which was both safe from magical community(from voldemort followers and fans equally) and also usefull in the spell.


When Lily died, she was standing in front of Harry's crib. So that's where her body would be when Hagrid went there. A genius like Dumbledore would've worked that out.

  • Worked what out? Just because she was stood by Harry's crib doesn't mean she made a conscious decision to sacrifice herself for Harry, by refusing Voldemort's offer to stand aside. Commented Jun 18, 2014 at 9:41
  • Also, James was (presumably) found in front of their house. How does anyone know James wasn't given the same choice, but declined as well?
    – SQB
    Commented Jun 18, 2014 at 10:46
  • @SQB Because if that was the case he wouldn't have got as far as Lily and Harry. Commented Jun 18, 2014 at 12:53
  • 1
    I am not sure why not. Pretty much any father would stand in the way of someone trying to kill his child no matter what the risk, why would James be different? V would have just killed him on sight and continued into the house.
    – Stefan
    Commented Jun 18, 2014 at 13:22
  • 3
    By the way, amogha, welcome to SF&F StackExchange. Unfortunately, your post doesn't really answer my question, so I'm guessing that's why it was downvoted (although not by me). Please don't let this discourage you, and hang around - who knows what great answers you may give later on.
    – SQB
    Commented Jun 18, 2014 at 13:57

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