This is how magic works:

Reality, Eric had learned from Merlin, is a massive, ongoing, limitless range of possibilities at any given moment. There are infinite universes, and only the limited senses of human beings narrow them down to what we see in front of us, the gross and simple world where things are shoved around by the blunt instruments of Newtonian physics.

But everything — every universe, and every moment in them — actually begins with information, which tells reality how to behave, and what shapes to take from the quantum level on up. Before anything exists, something has to instruct it how to fall into place.

The first element of reality isn’t time or space or gravity. It’s story.

Magic, Eric discovered, is nothing more than rewriting the story at that very basic level: using specialized information to create a new set of rules, creating a world out of the trillions of possible ones that exist.

This was much easier in places like Middleton, where the membranes between worlds were already thin.

There were different names for the ways to do this. Spells, sigils, rituals, sacrifices, magic words. All of them were different ways of doing the same thing: changing the story that holds the world together, or replacing it with a new one.

Merlin described it as weaving new threads into a pattern. Or he talked about writing in chalk on an engraved stone tablet. Or he would tell Eric about shaping clay into new forms.

Eric thought of it like cheat codes in video games. There were shortcuts that could change the rules, or alter the landscape of the game itself, if he pressed the right sequence on his controller. He could summon a big gun that never needed reloading, or get unlimited lives, or jump all the way to the boss level at the end. Magic was the same way. All the glyphs, spells, incantations, sigils, and rituals that Merlin showed him were like secret combo moves he could unlock. Eric could cancel gravity, push the weather around, and pick and choose from quantum probabilities.

Magic was possibility. All Eric had learned, really, was how to pick the right one. Sometimes.

But there was always a cost. Every roll of the dice, every rearrangement of the world, required a sacrifice. All that antichance had to be balanced. In this way, magic was depressingly like double-entry bookkeeping. The math had to even out somewhere. Merlin was still paying his debt for changing the world in the fifth century. Dark magicians, like Colchester, paid that price with the blood of others, because they honestly did not give a damn and they did not expect to be around when the final bill came due.