Question

Elena smoothed the curling edges of the vellum map across the oak table, weighting the corners with brass compasses. The map, dated 1842, depicted the jagged coastline of Cape Sorrow, a region notorious for its treacherous shoals and sudden, blinding fogs. Her fingers traced the delicate, hand-drawn hatching that represented the cliffs overlooking the sea. The ink was faded to the color of dried tea leaves, yet the draftsman’s precision remained sharp, capturing every indentation of the rocky shoreline where dozens of merchant vessels had met their demise. To anyone else, the map was a historical curiosity, a relic of a time when cartography was as much an art form as a science. To Elena, however, it was a puzzle waiting to be solved. She had spent the last three months in the basement of the Maritime Archives, surrounded by the scent of decaying paper and leather bindings, searching for clues about the lost voyage of the Saint Jude.

As her fingers brushed the tiny, hand-inked symbol of the lighthouse at the tip of the peninsula, the sounds of the quiet archive room began to fade. The soft hum of the fluorescent lights was replaced by the low, resonant rumble of the sea, and the air in the room suddenly felt heavy with the scent of brine and ozone.

Twenty years ago, when she was merely seven years old, Elena had stood on those very cliffs during a violent late-summer gale. She remembered the fierce wind tugging at her yellow raincoat, threatening to pull her toward the edge, and the salty spray that stung her eyes as she looked down at the churning ocean. Her grandfather, a retired mariner with skin cured by decades of ocean wind, had held her hand tightly, his grip a solid anchor against the storm. "Look closely, Elena," he had shouted over the roar of the surf, pointing toward the white water where the black teeth of the reef lay just beneath the surface. "A map doesn’t just show you where the land ends. It shows you where the stories are buried, and where the danger hides." That afternoon, after they had retreated to the safety of the lighthouse's circular kitchen, her grandfather had set a blank sheet of paper before her. With a stubby graphite pencil, he had guided her small hand to draw her first map—a crude, wobbly sketch of the kitchen table, the cast-iron stove, and the sleeping orange cat. It was then that she understood that paper could contain an entire world.

The shrill, metallic ring of the archives telephone snapped Elena back to the present. The salty breeze vanished, and the roaring ocean subsided into the hum of the archives' dehumidifier. She blinked, adjusting to the sterile, white light of the modern room. She looked down at the 1842 map, her hand still resting on the lighthouse symbol. But now, with her grandfather's words echoing in her mind, she noticed a detail she had previously overlooked: a tiny, faint notation of a shallow reef, marked with a symbol that matched the one her grandfather had shown her so many years ago.

What is the primary function of the flashback in the third paragraph?