The tea bag was invented by accident — and by a complaint.

Thomas Sullivan was trying to save money on tin sample containers. In 1908, the New York tea merchant started mailing small silk pouches of tea to potential clients — a cheaper, tidier way to send out samples.

His customers, apparently not reading any instructions, dropped the pouches straight into their teapots and brewed them whole. Sullivan never told them to do that. But it worked, and they liked it.

Then came the complaints. Not about the concept — about the mesh. The silk was too fine, customers said, and it slowed the infusion. Sullivan listened, switched to a looser gauze, and accidentally formalized an entirely new way to make tea.

The design iterated from there: gauze gave way to paper, square gave way to the now-iconic rectangular bag, and staples eventually replaced string. By the mid-20th century, tea bags accounted for the majority of tea sold in the United States.

Britain — the nation most associated with tea culture — held out longer. As late as 1968, loose-leaf still dominated British kitchens. Today, roughly 95% of tea drunk in the UK is brewed from a bag. The empire of loose leaf fell to a merchant's cost-cutting measure and a customer who couldn't follow directions.