In Harry Potter and the Prisoner of Azkaban, there is a passage about students having leeks growing out of their ears:

A number of small scuffles broke out in the corridors, culminating in a nasty incident in which a Gryffindor fourth-year and a Slytherin sixth-year ended up in the hospital wing with leeks sprouting out of their ears.

But is this not a violation of one of the "Principal Exceptions to Gamp's Law", stating that food cannot be conjured out of thin air?

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    You cannot conjure food but you can however transfigure something to look like food. I suspect that the leeks were a transfiguration. Note: Transfigured objects should not be eaten as they eventually return to their original state. Apr 20, 2016 at 2:43
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    This is my most favorite question ever asked on this site! Awesome! :D Apr 20, 2016 at 2:44
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    The Harry Potter and the Methods of Rationality reason that you can't Transfigure food is: you can transfigure food from (e.g.) wood, but it will probably kill you if you eat it because the Transfiguration will wear off after a while, and then your bloodstream is full of fragments of (e.g.) wood. In this context, Gamp's law says "you must not Transfigure food" rather than "you are somehow prevented from Transfiguring food". Apr 20, 2016 at 13:56
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    Wouldn't earwax count as a substance for transformation?
    – DWin
    Apr 20, 2016 at 17:13
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    @PatrickStevens -- It should probably be stressed that Harry Potter and the Method of Rationality is a fan fiction and is not canon. It's basically just theorizing, along with the rest of Harry Potter fandom. Personally, I don't mind theorizing -- it's enjoyable!. I just wanted to draw the distinction between a fan work and canon, though. :) Apr 20, 2016 at 18:40

2 Answers 2


Probably fairly well

First, keep in mind that Gamp's Law is from Harry Potter and the Deathly Hallows, and thus presents a later stage of Rowling's thinking than Prisoner of Azkaban.

That said, I think the leek spell is entirely consistent with Gamp's Law.

“Your mother can’t produce food out of thin air,” said Hermione. “No one can. Food is one of the first of five Principal Exceptions to Gamp’s Law of Elemental Transfigur—"

“Oh, speak English, can’t you?” Ron said, prising a fish bone out from between his teeth.

“It’s impossible to make good food out of nothing! You can Summon it if you know where it is, you can transform it, you can increase the quantity if you’ve already got some—”

Harry Potter and the Deathly Hallows

Hermione says that it is impossible to produce good food out of nothing. This suggests that is possible to produce something that has the appearance of food, but which provides no nutrition. I suspect the leeks coming out of the students' ears were in that category. Just as, presumably, one cannot eat the birds that Hermione conjured in Half-Blood Prince, regardless of their resemblance to real birds.


I like the answer by @Jonah.

However, There is another possible explanation:

Creating food seems to require a source that is already nourishing. The human body certainly fits that category. So the leek might be fueled by the victim of the spell. That would make it transformed blood and/or flesh.

  • What exactly do you mean by “creating food seems to require a source that is already nourishing”? What is a nourishing source? What is a source to begin with, in this context? And create how? Gamp says that you cannot create food with magic. Apr 20, 2016 at 9:14
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    Well, human blood is food, be it gross and somewhat dangerous (infection transmission is high across the same species), and hard to digest raw. But food, nevertheless.
    – P.Péter
    Apr 20, 2016 at 10:51
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    McGonagall: "Today's lesson, class: Transfiguring earwax into leeks." Dumbledore: "Alas! Earwax!"
    – Rand al'Thor
    Apr 20, 2016 at 11:08
  • You can't create leeks out of thin air, but you can transform ear wax or ear hair into leeks...
    – max pnj
    Apr 20, 2016 at 12:52

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