Check what you’re wearing right now, on a Saturday, doing nothing much. Somebody went on strike so you could.

For most of the industrial nineteenth century, the working week was six days, and the day itself ran ten, twelve, sometimes fourteen hours. This was not a custom; it was the deal on offer, and there was no other counter. The first factory acts trimmed hours for children before anyone in power conceded that adults might also be tired.

The demand that organized everything was almost embarrassingly simple: eight hours. “Eight hours for work, eight hours for rest, eight hours for what we will,” the movement’s song went, and the third clause was the radical one. On May 1, 1886, hundreds of thousands of American workers struck for it. Three days later, at a rally in Chicago’s Haymarket Square, a bomb and a volley of police gunfire turned the movement into martyrs, a trial into a scandal, and the date into a holiday. May Day is the world’s Labor Day because of Chicago, a fact the United States has spent more than a century politely not mentioning.

The weekend’s second parent was less romantic: an industrialist’s spreadsheet. In 1926 Ford Motor Company put its factories on a five-day, 40-hour week at six days’ pay. Henry Ford’s stated logic was that leisure was good for business, since a man with a free Saturday and a wage might spend both on an automobile. Unions had been making the human version of that argument for forty years. It’s telling which version made the newspapers approve.

Law arrived last, as it usually does. The Fair Labor Standards Act of 1938, one of the final big beams of the New Deal, set a federal ceiling on hours with time-and-a-half beyond it: 44 hours at first, then 42, then 40 from 1940 onward. It also banned most child labor and set the first federal minimum wage, twenty-five cents. The weekend as a legal default in America is younger than some people still collecting a pension.

None of this was given. That’s the part worth printing on a shirt. Every norm in your calendar was somebody’s impossible demand two generations before it became furniture, and the arrow runs the other way too: what was won by negotiation can be lost by attrition, one “flexible” scheduling app at a time.

Enjoy the Saturday. It has a receipt.