In the state of Song an artisan carved a mulberry leaf out of ivory for the King. It took him three years. The ivory leaf has a pleasing shape, delicate veins, fine hairs and lustrous color. When placed among real mulberry leaves, it was indistinguishable from real ones. The man received a generous stipend from the King for his accomplishment.

Lie Zi heard about this. "If it takes three years for Mother Nature to produce a single leaf," he pointed out, "then there would hardly be any trees with leaves in the world."