Think back over the rat’s making. A creature born to blackness sees one match flare and cannot forget it. His teacher swings a locket and preaches suffering. Upstairs, the light he longed for turns him ridiculous in the one moment the whole court is watching; a queen dies of the sight of him. And fleeing, he looks for mercy in the brightest face in the kingdom — and finds disgust. The spoon he steals is heavy. The vow he makes is heavier.

In the crowded art workshops of Renaissance Italy, painters perfected a technique they called chiaroscuro — ‘light-dark’ — building a picture not from outlines but from the war between brightness and shadow. Earlier panels had often been lit evenly, corner to corner, so that nothing in them pressed forward and nothing fell away. A face lit by a single candle; a room that is mostly night; one white sleeve blazing out of blackness. The strong contrast did what soft, even daylight could not: it made paintings feel like moments — caught, dramatic, alive.

The master of the method was Caravaggio, whose canvases seem lit from within by torchlight. He understood the technique’s secret, which is really a rule of seeing: light means most where dark presses closest. A candle at noon is nothing; the same flame in a cellar can illuminate a whole story. Viewers feel that difference long before they can name it, which is why the trick has never gone out of use. Writers borrowed the idea from the painters — heroes shine brightest in their darkest chapters — and one modern storyteller went further still, and named a dungeon rat for the technique itself.

No right or wrong — close the screen and tell someone nearby what happened in this part. Can’t find anyone? Tell yourself out loud. The moment you teach it, you truly understand it.