Cook Ding’s Blade

Ordinary cooks change knives every month, because they hack. Good ones change them once a year, because they cut. Nineteen years he has had this one, and thousands of oxen have gone under it, and the edge is as though it had just come off the stone.

He waits for the seam and goes in where there is already room. The blade has no thickness. That is why nothing of it has been used up.

— after Zhuangzi, chapter 3, “The Secret of Caring for Life”