In Borges' shortest and most cunning betrayal story, an Englishman in Uruguay tells a stranger how he came by the crescent scar across his face. He calls it the inheritance of an Irish revolutionary named John Vincent Moon — a coward who sold out his comrades to the Black and Tans during the war of independence. The narrator presents himself as Moon's victim — the comrade Moon betrayed; before fleeing, the narrator carved a crescent into the traitor's face with a curved blade. In the last sentence, the speaker breaks the spell. I am Moon. He has been telling the story all along in the first person of the man he betrayed — the only voice in which he can bear to confess.
The scar is the story's algorithm. Before any word is spoken, before the narrator decides which version of himself to perform for the visitor, the geometry of his face has already announced the truth. A crescent moon, etched in flesh, is the literal shape of the syllable Moon — his own surname inscribed on his cheek by the man he betrayed. When you commit a particular act of cowardice, Borges suggests, your body becomes the equation that solves it. The face is a parametric function: f(t) = scar(t), and the scar ends, deterministically, at the shape of your own name.
To visualize this story is to draw a curve. The single line that crosses the canvas above is computed in real time — a sine-modulated arc whose endpoint must, by construction, be a crescent. You can hover near it and read fragments of the betrayal that are deterministic from your cursor's position; you can click anywhere along its length and the wound becomes a Borgesian micro-confession, generated from those exact coordinates. Two visitors who click the same point of the scar receive the same paragraph. The scar is not painted — it is solved, the way Moon's face was solved by the sword that wrote it.
The strangest grace of La forma de la espada is its first-person inversion. To accuse oneself in one's own voice is, Borges thinks, almost impossible: the I is too thick with self-defence. So Moon borrows the voice of the man he betrayed, and through that borrowed mouth says everything he could never say as himself. The oracle at the top of this gallery offers the visitor the same trick — type a confession in the first person, and the curve will accept it as its own, lettering your sentence along the scar. The page will note: I, John Vincent Moon, was once braver than this. I am writing in the first person of the man who betrayed me. That is the algorithm of the story: the only confession that names itself does so in the voice of someone else.