When the lower classes adopt the fashions of the elite, the elites often respond by changing course abruptly—a neckline or a hemline rises or falls dramatically, perhaps, or a voluminous silhouette narrows. But sometimes, rather than quickly changing styles, the upper classes simply wear the clothes the poor have discarded.

For example, as towns populated in the 14th century, a merchant class arose within them. This middle class had some discretionary income, and they spent it on the most conspicuous consumer good: clothing. Finally, they could afford jewel-studded velvets, gold and silver trimmings, brightly colored coats, and sumptuous furs. As the fashion historian Anne Hollander has explained, when the aristocracy couldn’t outlaw or outspend these medieval nouveau riche, they started wearing baggy and threadbare clothing. This new fashion—looking like one had thrown on any old thing—served as a not-so-subtle reminder to the upstarts that, while money could buy clothes, it couldn’t buy class.

Blue jeans offer a more recent example. Jeans began as cheap and durable work pants for miners and farmers. They were the de facto uniform of the rural working class. But once working-class men had access to ready-to-wear trousers, their jeans started showing up on postwar suburban youths, and then in trendy boutiques. Recently, Nordstrom even sold a $425 pair of jeans with fake mud stains—the ultimate blue-collar costume. Once more, the wealthy turn the tables by appropriating the clothing of the poor.

The LBD also finds its origins among the poor. Before the 19th century, domestic servants wore whatever they could—homemade dresses, often, but also their employers’ hand-me-downs. But in the 1860s, the British upper classes required their maids to wear a common uniform: a white mobcap, an apron, and a simple black dress. Soon after, wealthy American and French families followed suit.

Relationships between upper-class women and their servants had changed, becoming “less intimate and more authoritarian,” as the sociologist Diana Crane puts it. At this time, servants ceased to be “the help,” a somewhat collegial characterization, and became known as “domestics.” And domestics wearing upper-class castoffs, especially young and pretty ones, led to embarrassing mix-ups. A caller mistaking the maid for the mistress of the house raised uncomfortable questions about recently erected class barriers.

Cassell’s Household Guide, which billed itself as an encyclopedia of domestic and social economy, summed up the problem like this, circa 1880: “As a general rule, ladies do not like to see their maids dressed in the clothes they themselves have worn—the difference in the social scale of mistress and maid renders this unpleasing.”

But Cassell’s made one exception: “a black or a dark-colored silk.” Previously, a simple black dress meant a wealthy woman was “dressing down.” But by the 19th century, the black dress had become a staple of the lower and middle classes. It was the perfect hand-me-down for the help.