There are metals we see everywhere.

Gold.

Silver.

Iron.

And then there is copper.

Copper is different.

It is hidden inside the walls, beneath the streets, inside machines, behind electrical outlets, under floors and inside the infrastructure that makes modern civilization possible.

For thousands of years, humans used copper for water, tools, vessels, medicine and technology. Ancient traditions recognized properties of copper long before modern microbiology existed. Modern research has confirmed that copper can damage microorganisms through several mechanisms. 

Then something happened.

Materials began changing.

Copper pipes became plastic.

Copper telecommunications became fiber.

Copper applications encountered aluminum and other substitutes.

The change is not imaginary. Material-substitution literature explicitly discusses aluminum, plastics and fiber optics as competitors or substitutes for copper. 

But why?

The conventional explanation is straightforward:

Cost.
Manufacturing.
Weight.
Corrosion.
Installation.
Technology.

Those explanations may account for much of the story.

But perhaps not all of it.

This book asks a different question:

What happens when a civilization changes the materials that surround its water, electricity, homes and bodies?

And more importantly:

Did we simply replace copper because newer materials were better suited to particular jobs—or did we gradually forget what copper itself could do?

That is the mystery.