In ancient times, people believed the sky was round and the earth square, held up by four heavenly pillars.
However, as the years passed, the four pillars that held up the sky weathered under sun, rain, snow, and storms, and the heavens began to falter. Cracks appeared in the sky, and rainwater poured down, flooding much of the land; lightning sparked forest fires, turning vast areas into seas of flame; fierce beasts roamed unchecked, preying on humans; and cruel birds of prey snatched the weak and elderly. Humanity found itself in grave danger.
Seeing humanity on the brink of destruction, the goddess Nuwa resolved to repair the heavens and save her children. She ignited a sacred fire, smelting red, yellow, blue, white, and black stones into five-colored gems, using them to patch the sky's cracks. Then, she captured a giant turtle, cut off its four legs, and set them as pillars to replace the broken supports of the sky.
The rain that leaked from the sky was caused by a black dragon causing mischief, so the goddess Nuwa bravely fought the dragon and finally killed it, eliminating the source of evil.
Thanks to the goddess Nuwa's tireless efforts, the sky was mended, the heavenly pillars were secured, and the fierce beasts were vanquished. Across the nine provinces, all was restored to order, and humanity could once again live in peace.
Later, the idiom "Mending the Sky with Smelted Stones" came to describe the great achievements made in saving a grand cause.
Source: *Huainanzi*, Chapter "Surveying Obscurities"
Meaning of the Idiom: Later, the Chinese idiom "炼石补天" came to describe how the great achievements made in saving a grand cause.