How does it work? In essence a blade is just a wedge. It allows us to concentrate a large amount of force into a tiny space.

The narrower the cutting face of the blade is, the more force is concentrated into the area. As an example, if you put a 1 lb weight on a one inch cube that cube will have a force area of 1 psi. If you put the same weight on a .1” cube it will be 10 psi, if you put it on a .01” cube you get 100 psi, etc.

When you think about a knife the edge is so thin you cant really see it with a naked eye, its tiny so any reduction of the edges area is going to result in huge changes of pressure at the cut.

The photo is an electron microscope view of steel as it is sharpened, starting with a coarse grit and getting finer. The fourth photo illustrates the wire edge often left behind.