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.

Before leaving his post as Qi chancellor in 193 bc, Cao Can gave advice to his successor: “If you stir up the markets and empty out the jails, then evil men will have no place to stay and will make trouble for you elsewhere.” A footnote in the English text from translator Burton Watson explains: “It was an assumption among Han officials and intellectuals that most, if not all, men engaged in trade were swindlers.”

One of the most extensive surviving archives of Old Babylonian writing consists of letters sent to Ea-nasir, an eighteenth-century-bc copper merchant from Ur. “You have offered bad ingots to my messenger,” complained one trading partner. “Who am I that you are treating me in this manner?” Another customer appears repeatedly in the archive, each time inquiring about a missing copper shipment. “Do you not know,” he wrote in his third missive, “how tired I am?”

Including trademarks in books became crucial after the invention of the printing press; without stringent copyright laws, rival publishers could repurpose superiorly edited texts with impunity. Aldus Manutius of Venice, who employed Erasmus as a proofreader, called attention to his company’s “sign of the dolphin wound round the anchor.” Florentine printers were aping the mark, but in the frauds, “the head of the dolphin is turned to the left, whereas that of ours is well known to be turned to the right.”

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.