Gamp's Law of Elemental Transfiguration

• Type: A fundamental law of magic, specifically governing the practice of Transfiguration.
• Proponent: Ulick Gamp (Pottermore).
• Primary Principle: It is impossible to conjure something from nothing (ex nihilo creation).
• Key Feature: The law is defined by its five “Principal Exceptions,” which are categories of things that cannot be created from nothing.

Gamp's Law of Elemental Transfiguration is a major governing principle of magic that sets the limits of what a witch or wizard can create. It establishes that while Transfiguration is a powerful and versatile branch of magic, it is not without rules. The core tenet of the law is that it is impossible to create objects or substances ex nihilo, or “out of nothing.” Instead, most acts of conjuration are a form of summoning, where an object is transported from another location, or transformation, where one object is changed into another. The law is most famous for its five Principal Exceptions, which are five specific things that cannot be created from thin air by any magical means.

The defining “property” of Gamp's Law is its set of exceptions. While the law applies broadly, there are five specific categories of items that are impossible to create from nothing. Of these five, only one is explicitly named in the original novels:

• Food: This is the most frequently discussed exception. As Hermione Granger explains, a wizard cannot create food from nothing. However, magic can still be applied to food in other ways:
  • It can be summoned if the user knows its location.
  • It can be transformed (e.g., turning a mushroom into a rat, though it would be an inedible one).
  • Its quantity can be increased if a small amount already exists, a magic frequently used by Molly Weasley to feed large groups of people.

The other four Principal Exceptions are not named in the seven books.

The law is first named and explained in 1997 during the hunt for the Horcruxes.

• After escaping the Ministry of Magic, Ron Weasley complains about their lack of food and suggests Hermione Granger simply conjure some. Hermione corrects him, stating that food is the first of the five Principal Exceptions to Gamp's Law of Elemental Transfiguration. She clarifies the nuances of what can be done with existing food, such as multiplying or summoning it (DH15).
• Later, while taking refuge in the Room of Requirement, Ron Weasley perfectly recites Hermione's explanation of the law to Harry Potter after Aberforth Dumbledore provides them with food, demonstrating his retention of the principle (DH29).
• The existence of the law also implicitly explains long-standing situations in the wizarding world, such as the Weasley family's poverty, as money and other valuable materials cannot simply be conjured into existence.

Gamp's Law serves a crucial world-building function by placing clear and logical limits on the power of magic. It prevents magic from being a deus ex machina that could solve any problem, thereby creating narrative tension and stakes. By making food impossible to create from nothing, the law makes the struggle for survival faced by Harry, Ron, and Hermione during their hunt for the Horcruxes more realistic and dire. It grounds the magical world, explaining why societal issues like poverty persist and why wizards cannot simply create infinite resources. The law forces characters to be resourceful and underscores the theme that magic cannot solve all of life's fundamental problems.

• The law is presumably named after its creator. The Pottermore website identifies this individual as Ulick Gamp, who served as the very first Minister for Magic from 1707 to 1718 (Pottermore).
• J.K. Rowling has stated in interviews that she has a very clear idea of what the other four exceptions are but has not made them public, as the information was not necessary for the plot of the books. This has led to considerable fan speculation about what else cannot be created, with common theories including love, life, and true knowledge.
• In the Part 1 film, Hermione's explanation of the law is mostly faithful to the book, occurring as the trio sets up camp in a forest shortly after their escape from the Ministry of Magic.