Herodotus reports that after Cyrus the Great was warned by a Spartan herald not to tread further into Greek lands, the Persian king received a primer on Sparta, including an explanation of an agora, to inform his response. “I have never yet been afraid of any men,” he told the herald, “who have a set place in the middle of their city where they come together to cheat each other.”

When Arctic traveler Vilhjalmur Stefansson traded with the Inuit of Victoria Island in 1911, he found the metal of their knives to be of curious provenance: Inuit to the east had bought guns from the Hudson Bay Company and traded them westward; the firearms were then traded farther west, eventually reaching the Inuit he’d met—who, having no use for guns, had beat the metal barrels into knife blades.

A thirteenth-century Song dynasty text about commerce describes dangers faced by pearl divers, who sometimes fell prey to “huge fishes, dragons, and other sea monsters” that would rip open their stomachs or bite off their feet. A pearl was considered most valuable if perfectly round; the test was “that it will not cease rolling about all day when put on a plate.” To avoid heavy export duties, foreign traders sometimes concealed pearls in canes or umbrella handles.

The head female of a paper-wasp nest allows others to occupy space in her home—so long as they help raise her offspring. The labor market is, however, elastic: if other nests nearby have childcare needs, she maintains a lower work requirement from her “helper” wasps.

A seventeenth-century rabbinical decision tells of a German town in which wealthy Jewish households kept chickens, while poorer women secretly milked gentiles’ cows early in the morning to sell the purloined milk on the street. One time, some chicks hopped into a tub of milk left on a doorstep and drowned. “Each side suffered a financial loss,” the text reads. “One from the milk, the other from the drowned chicks.”