The effect at the heart of the film
The Transported Man
Borden walks on stage, bounces a rubber ball across the boards, steps into a cabinet on the left, and in the same instant steps out of a cabinet on the right to catch the ball. No lights, no music, no assistant, an effect so bare that Angier cannot believe it and cannot leave it alone. That is a very accurate portrait of how an illusionist reacts to a competitor's best piece. Angier's first answer is Gerald Root, a drunken double hired to step out of the second door; Borden's answer is the one Cutter guessed from the start. You do not admire it first. You want the method.
The film offers two methods, and they are the whole argument of the story. Borden's version is pure craft: a secret so simple that Cutter guesses it in his first sentence, kept at a cost that reaches into every hour of Borden's private life. Angier's version is bought: he travels to Colorado to commission a machine from Nikola Tesla, played by David Bowie, and the machine does something no conjuror could do. One man pays with his life as it is lived; the other pays with money and then, night after night, with something worse. The ending turns on a sacrifice the film shows only at the very end.
What the trick would really take
Stage magicians have performed instant transpositions for a century and a half, and the honest answer is that there are only a handful of ways to do it: a double, a very fast route the audience cannot imagine, or a cabinet that is not what it seems. Priest and Nolan knew this. The genius of the film is that it gives Borden the method the audience refuses to accept because it is too obvious, then gives Angier a method that is impossible, and asks which one is the real cheat. In a theatre, Borden's is the only one that exists. It is also the one that demands the most.
Hugo does not perform transpositions; his field is the mind rather than the cabinet. But the lesson transfers. When he reads a thought in a room of two hundred people, the audience assumes a complex method and is usually wrong in the same direction as Angier: the secret is rarely a machine. It is preparation, discipline and the willingness to do the dull part perfectly every time.