Back when I was learning swordsmithing in a Glastonbury forge, we'd start our days aiming to make the perfect nail and we'd finish the day in the same fashion. A hard feat, you had to be quick and your strokes confident, brave.
The forged nail can hold that which can't stand on it's own and bring together what's set apart, bind one thing to another.
It is the most ancient way we've found to strengthen our physical world but it also carries in some of our own. Our ancestors believed that celestial qualities corresponding to the time at which the nail was struck into its medium can be bound into workings.