To help me expand this into a longer narrative or a different genre:

For years, Elias had lived in a world of muted grays and dusty browns, a reflection of the creative block that had anchored his soul. Then, he found the glass. It wasn't a window he had bought, but a gift from a traveling glazier who claimed the panes were salvaged from a fallen cathedral of light.

(what happened to the man who gave him the glass?)

The sunlight didn't just enter Elias’s attic studio; it shattered.

and I’ll build out the next chapter.

He didn't just see the colors; he felt them. The red was a low hum in his chest, and the cyan was a cool breeze against his neck.

People began to notice. They said his new work looked like it was illuminated from behind, even in the dark. They called it "The Prism Collection." But Elias knew the truth: he wasn't the artist. He was just the scribe for a window that spoke in every language of the light.

Under the spell of the fractured light, Elias began to paint again. He didn't paint landscapes or portraits; he painted the window's song. By the time the sun moved past the eaves and the room returned to its dull gray, his hands would be stained with the ghosts of the spectrum.