All Knives Are Serrated

A very sharp knife looks (as seen by the naked eye) to have a perfectly continuous edge formed by the intersection of two perfectly smooth surfaces. But the edge of a very sharp knife is, in fact, (as seen under powerful magnification) a jagged, impassable ridge line formed by the intersection of two rugged slopes.

A knife edge polished to a mirror finish—relatively smooth even at the microscopic level—doesn’t cut better. It may not even cut as well because the tiny imperfections of the edge are what actually do the work of tearing and dividing the material*. A knife does it’s work a little at a time on a very small scale. A little progress here and there, over and over again, over the length of the strokes. Not perfectly, but persistently.

Just like us.

* A note to my wood-working friends: I acknowledge this is not the same for a chisel or other tools with a similar action.