How do you think a spade, sword or dagger wounds us? Because the metal is a form of matter in which the particles are closer and more tightly bound together than those of your flesh. The metal forces flesh to yield to strength, just as a galloping squadron penetrates a battle line that is of much greater extent.
And why is a piece of hot metal hotter than a piece of burning wood? Because the metal contains more heat in a smaller volume. The particles in the metal are more compact than those in the wood.

The Other World (1657)