Many years hence, the printing press that inked these black words on this sheet of paper is going to be scrap metal.

Responding to a changing world, newspapers and countless other enterprises are migrating to the Internet. Such is the history of technology; people abandon old methods when new ones deliver the goods more quickly and cheaply.

That’s the necessary context of the postmaster general’s plan to stop home mail delivery on Saturdays. Lots of people are yelping: lawmakers, postal unions, farmers and rural communities. They’ve got their fingernails dug into the 20th century, clawing to keep it from rolling out of sight.

Patrick Donohoe should instead be applauded for trying to keep the United States Postal Service alive.

Those who want Saturday deliveries and business as usual are trying to keep a dinosaur breathing on life support.

The digital age hasn’t been kind to the traditional letter-in-an-envelope. The USPS has lost 25 percent of its business in the past five years – and it has been increasing the price of first-class stamps relentlessly. It now costs 46 cents to send a letter the old-fashioned way.

Without radical restructuring – something Congress has refused to allow – the postal system is headed for a death spiral. It’s far cheaper to communicate online; raising the price of postage will push yet more communications online, and leave less revenue to sustain the USPS’s oversized infrastructure.

Clamoring for the good old days of six-day delivery only undercuts the system’s odds of survival. Cutting Saturday service, in fact, must be followed by closures of thousands of small post offices and other money pits that are dragging the system down.

Congress doesn’t get this yet. Most Americans appear to understand that the status quo can’t be perpetuated, but the people who resist change are so vociferous that they’ve spooked many lawmakers.

Although Congress doesn’t fund the USPS, it keeps an iron grip on its business decisions, tying the hands of Donohoe and other administrators. Dropping Saturday mail deliveries is an obvious, rational way to wring $2 billion a year out of postal operations, but some lawmakers are threatening to reverse the move.

Two words sum up the postal system’s predicament: “snail mail.” The world will not be returning to 20th-century bills and letters.

The paper envelope will eventually be a historical curiosity. Today, people pay bills, order groceries and even get junk mail online.

The bright side, for the USPS, is that package delivery is a growth industry. Somebody has to deliver those orders from Amazon, and Donohoe intends to keep the USPS doing that on Saturdays. Change can hurt; it can also offer opportunities.