A few years back, I wrote an essay on creating magic systems that I titled Sanderson's First Law. It had to do with the nature of foreshadowing as it relates to solving problems with magic. In that essay, I implied that I had other "laws" for magic systems that I'd someday talk about. Well, that time has come, as I've finally distilled my thoughts for the second law into an explanation that will work.

I'll start, however, by noting that none of these "laws" are absolute. Nor am I the only one to talk about them. By calling them "Sanderson's Laws" I'm merely referring to them in the way I think of them—they are rules I try to live by when designing magic systems for my books. There are a lot of ways to write, and the only real "laws" are the ones that work for you.

These work for me. I think they are actually all principles of good writing, not just writing as it pertains to magic systems. However, because magic systems are one of the things I most like to toy with in my writing, I have designed them in such a way that they encourage me toward stronger, and more interesting, magic in my fantasy books.
The Law

Sanderson's Second Law can be written very simply. It goes like this:

Limitations > Powers

(Or, if you want to write it in clever electrical notation, you could say it this way:

Ω > |

though that would probably drive a scientist crazy.)

Let's do some explaining here. When people describe a magic system, they usually talk about what it can do. Let's use a very well known example: Superman. (Yes, superhero abilities are a magic system. In fact, many of them make for good examples, since many of them are well known in society and the scope of their powers is fairly well pinned down.)

If I were to ask you about Superman's magic, you'd probably talk about his ability to fly, his super strength, the lasers he can shoot from his eyes. You may go from there to his invincibility and perhaps some of his lesser (and more inconsistent) powers. But if we stick with those four, we've got a pretty strong setup for what Superman is capable of doing.

However, is this what makes Superman interesting?

I'd put forth that it is not. There are lots of people with magic powers who can fly and who are invincible. There are a lot of strong, fast, or smart people. What makes Superman interesting, then? Two things: his code of ethics and his weakness to kryptonite.

Think about it for a moment. Why can Superman fly? Well, because that's what he does. Why is he strong? Comic book aficionados might go into him drawing power from the sun, but in the end, we don't really care why he's strong. He just is.

But why is he weak to kryptonite? If you ask the common person with some familiarity with Superman, they'll tell you it's because kryptonite—this glowing green rock—is a shard from his homeworld, which was destroyed. The kryptonite draws you into the story, gets into who Superman is and where he comes from. Likewise, if you ask about his code of ethics—what he won't do, rather than what he can do—we'll go into talking about his family, how he was raised. We'll talk about how Ma and Pa Kent instilled solid values into their adopted son, and how they taught him to use his strength not to kill, but to protect.

Superman is not his powers. Superman is his weaknesses.
What This Means for Writers

Now, that explanation above is a descriptive point. It illustrates a concept, but is just an example, working backward. And yet you'll find this concept repeated time and time again in fantastical fiction. It isn't what the heroes can do that is most important to who they are, but what they have trouble doing. (Or what they can't do.) The Lord of the Rings is not, when you boil it down, about Gandalf's magical powers or even Aragorn's orc-slaying skills. It's about the Hobbits, arguably the weakest (physically and magically) of the people in the books. It's about Aragorn's struggle to become king.

(The films, it should be noted, played this concept up much more than the books did, as the director realized Aragorn became far more interesting when he was reluctant to become king. His weakness gave him much more depth than his abilities.)

Now, this concept won't hold in every example. And, more importantly, the average reader will miss this concept entirely. That's okay. This law is meant for writers.

When you are designing a magic system, it is important to be working on new slants on powers. However, the truth is that it's virtually impossible to come up with a magical effect that nobody else has thought of. Originality, I've seen, doesn't come so often with the power itself as with the limitation. Take the Wheel of Time, for an example. This is a very popular epic fantasy series, and one I've long loved and had the privilege of being a part of. The magic system, at its core, is actually rather generic. People can manipulate the Aristotelian elements. Fire, earth, water, air, with the commonly added fifth element of spirit.

This core is not original. It's the limitations, costs, and weaknesses of the magic system that bring us its more fascinating elements alongside its best plot hooks. In order to manipulate these five powers, practitioners draw forth "threads" of them and then "weave" the different powers into complex patterns, which then accomplish a goal. This is a limitation of the magic. Instead of merely willing something to happen, then having it happen, the practitioners must use skill and knowledge, and take time to create what they're making. It also gives a visual component to the magic system (always an excellent addition) and—beyond that—ties the magic into the cosmology of the world. (In the Wheel of Time, the mythology of the setting teaches that everyone's lives are threads woven into the pattern of time.)

On top of this, Robert Jordan added one of the most powerful costs to a magic system that I've ever read. Men who use the magic go slowly insane. This cost is wonderful, as it makes the magic worth something. It forces the characters to make tough choices, and then it shows real, story-based ramifications.

These are the sorts of things you should be looking for as a writer designing magic systems. (Or as a reader who is curious about the workings of fiction.) An excellent limitation on a magic system will do several things.
Struggle

It will force the characters to have to work for their goals, which makes the writing simply more interesting and the characters more sympathetic. In addition, if a magic is limited, the characters will need to be more clever to overcome their problems. (And you, as a writer, will need to force yourself to be more clever in writing.) For example: in Mistborn, the practitioners of the magic can move things with their minds. Basic telekinesis. However, there are two important limitations. The objects must be metal and the magic practitioner can only push them directly away or pull them directly toward themselves. The weight of the object is very important—a light object is pushed away, a heavy object pushes you away.

Suddenly, with these limitations, the characters are forced to work harder. And, in working harder, the written scene becomes much more interesting. Instead of a ho-hum scene with a character doing something abstract, the author ends up writing a scene where a character has to be very aware of their surroundings, has to place themselves very precisely, and has to work to achieve their goals. The nature of the magic encourages better writing.
Tension

An excellent magic system limitation will increase tension. Superman fighting an enemy is, honestly, not very tense. Superman fighting an enemy with kryptonite is far more tense. Batman fighting an enemy is not very tense. Batman fighting an enemy who is playing off of his inner fears (the current Batman's biggest weakness being his psychological problems) suddenly becomes far more interesting.

Limitations give us tension. Too often, I see new authors leaving out excellent opportunities like this. From there, they end up writing bland scenes with magic that happens abstractly in ways we can't relate to as readers.
Depth

You can do this with powers too. You can do this one with anything. However, my experience has been that great limitations require a little more stretching to explain. That forces you, as a writer, to create more depth to your world and characters. If you have a character whose power is the ability to fly, but then you add a limitation—she can only fly when she is happy, for example—then character depth will result. Suddenly, her mood is directly tied to the plot of the story. Her very personality is going to be involved deeply in her ability to accomplish things with her magic.
Limitations vs. Weaknesses vs. Costs

I have been lumping all kinds of different things under the heading of "limitations" for this essay. However, it's useful to consider these elements in different lights. I generally think of the limiting factors of magic systems under three headings.
Limitations

These are the things that, for one reason or another, the magic simply cannot do. Superman can't see through lead, for example. Every magic has basic limitations, defined simply as the limited scope of the power. If magical glasses can let you see a mile, then the limitation is that they don't let you see farther than that.

However, in regards to designing magic systems, I suggest that the limitations be more encompassing than simple parameters. Yes, those delineations of what the magic can and cannot do are important, and that is where you begin. However, one of the tricks to designing a truly engaging magic system is in the final touches of those limitations. I'm not saying they always need to be rational—having a rule-based magic system isn't about rationality, but consistency. (Of course rationality is always advisable, but sometimes impossible. We are talking about magic, after all.)

Let's look at a magic system with an interesting limitation, David Eddings's magic known as the Will and the Word. Now, this is basically an unbounded magic system with very few limitations other than the strength, skill, and endurance of the practitioner. (Alongside the occasional conservation of energy quirk.) However, it does have one rather intriguing limitation—you can do practically anything, but you cannot "unmake" something. You can't command something to "be not."

I've always liked this limitation because of its flavorful addition to the magic system. Rather than just being another boundary—you can't use the magic when you're too tired, or a similar basic limitation—it is an evocation of what the magic is about and what it means. This is the power of creation. It cannot unmake, and anyone who tries to use it to unmake is destroyed by the very nature of the power itself.

In seeking limitations, look for things that have good ties to the nature of your world. Also look for things that will force your characters (and you as a writer) to stretch in solving problems. Resist the urge to add new powers or remove limitations in order to solve problems; make the characters use what they have in new and innovative ways.

Without limitations, there is no innovation.
Weaknesses

Weaknesses are different from limitations. Weaknesses are things that enemies can exploit—rather than being things the power cannot do, they are things the power is vulnerable to. The obvious example from the essay earlier is kryptonite.

I realize this is a matter of semantics. In a way, a weakness is just another limitation. I believe it is helpful for the writer to look at them differently, however. It is not a weakness that your magic allows you to jump a hundred feet into the air, but not two hundred feet. That's simply what the power does, the bounds it has. It is a weakness, however, if your ability to jump into the air leaves you vulnerable in some way, such as turning off your other powers. (Perhaps one needs to focus all energy on this single act.)

Weaknesses are more tricky to build into a magic system; I find it difficult to keep them from seeming simplistic or silly. As good as kryptonite is for explaining the importance of limitations, it's become a cliché of easy storytelling. Need a weakness for your hero? Just take away their powers in certain circumstances.

I suggest avoiding such simple weaknesses. Once again, the purpose of building these weaknesses is to create a better story. Yes, a weakness can be a good way of checking a hero who has grown too powerful—but in the case of most magics, I suggest allowing the limitations to be what force this issue, not suddenly added weaknesses.

They can be used for great effect, however—I simply suggest making them subtle. Ways the magic is vulnerable or makes those using them more vulnerable. In fact, one might say that weaknesses are the bridge between limitations and the next category, which is an excellent way to limit a powerful magic.
Costs

The One Ring makes you more covetous and paranoid the longer you hold it—and, beyond that, if you use it to turn invisible, the evil powers can sense where you are. These things are what we call "costs." Using the magic, or being associated with it, has a cost. These costs can be more abstract (you go crazy by using the magic) or more concrete (if you run out of spice, you can no longer travel faster than light in space). The distinction here is how much wiggle room the author has.

In the first example, what it means to be "insane" is left up to the author's discretion. There are lots of different types of insanity, and how quickly someone goes insane—and what it means to be insane—are things that, as a writer, you can play with. In the second example, the cost is more concrete, locking the author into a certain specific cost. If it takes three magic beans to make the doorway appear, your character has to have the three magic beans. That's it.

Both are useful for different reasons. Costs are very important to consider—readers naturally expect there to be a cost, and a lot of times, new writers skimp on giving their magic one. However, do be aware that if your cost is too drastic, it can lead to you never being able to use the magic. If casting a spell causes one of your grandparents to die, then we're just not going to be able to see that spell used very often in your book. It's easy to lock yourself in with a cost and it can hinder flexibility.
Others

These definitions are simply ways of looking at the issue. They aren't catch-all categories. You can approach this in another way by asking yourself questions, and not allowing yourself to take the easy answers.

How does one gain access to the magic? The standard two methods are innate magic and learned magic. (Or a hybrid.) You can really make your magic stand out if innate limitations require a different way of gaining access to the magical powers.

How is the magic powered? All magic, to one extent or another, is going to break the laws of physics. However, you can mitigate this by asking yourself about preservation of the laws of thermodynamics. What is powering this magic? Where is the energy coming from, and where does the matter go? Once again, there are standards: the practitioner's willpower is one, the power of the universe, such as an amorphous "force," is another. (I used one of these in Elantris, and this is how the Wheel of Time magic is powered. These aren't bad, but—once again—if you avoid the common, it can be a good way to force yourself to be original.)

How often can the magic be used? Does it require special implements? A special state of mind? Special ingredients? Once again, stay away from the standard. Look beyond what your first responses are.

Above all, remember the point of this. It is not to simply be more complex. It is to force you, as a writer, to create better stories. Therefore, the best limitations will have real effects on the characters, rather than pretend ones (i.e. the magic requires special implements that have no real effect on the plot, no real emotional or economic cost, and which the characters are never without). Look for things that tie the magic to other setting elements and which make life hard for the practitioners in interesting ways.
Not Just a Principle of Magics

I'll close this essay by turning back to something I mentioned above. I don't see Sanderson's Laws of Magic as only relating to magic. I see them as storytelling principles, illustrated through ways one can design better magic systems.

So, in reality, this is a larger storytelling concept. Limitations are more important than abilities. It applies to characters—what they cannot do, what they won't let themselves do, is more interesting in general than what they can do. It applies to worldbuilding. The costs of living in a harsh world are more interesting, often, than the benefits. (Think of Dune, for example.) The weaknesses inherent in the flora, fauna, and local building materials of your world are more interesting than what can be found there. (Notice in the film Avatar, the story is not really about the precious ore being mined, but in the difficulties in getting to that ore.)

And, if we bring this out to a broader issue, what your characters have trouble accomplishing in a plot is going to be far more interesting than what they can do easily. Remember that one simple rule, and your stories will be far more compelling.

Brandon Sanderson
April 2011