From ‘watershed moments’ to ‘windfalls’

Even if you’re not familiar with computer firewalls, you could guess from the word that they are meant to stop something dangerous. Firewall conjures up either an impenetrable wall made of fire, or a wall intended to stop a fire’s spread. Two other common elemental words, watershed and windfall, take a little more figuring out.  

When the U.S. Senate passed a same-sex marriage bill, The New York Times called it a “watershed moment.” The United Nations biodiversity summit produced a “watershed agreement,” according to The Washington Post. The news media seem to love the word watershed, “a crucial dividing point, line, or factor” as Merriam-Webster puts it. 

Geologically, though, a watershed is a drainage basin, “a land area that channels rainfall and snowmelt to creeks, streams, and rivers, and eventually to outflow points such as reservoirs, bays, and the ocean,” according to the National Oceanic and Atmospheric Administration. A “drainage basin” seems too passive to be used, metaphorically, to indicate “a turning point.”

Originally a watershed was more like a firewall. When it first appeared in 1764, the term referred to mountain ranges, hills, or other high areas that divided drainage basins. According to the Oxford English Dictionary, a watershed was “a narrow elevated tract of ground between two drainage areas; a water-parting.” Shed, in this case, comes from the Proto-Indo-European root skei-, “to cut, split,” like the German verb scheiden, “to divide; to divorce.” The Continental Divide is this kind of watershed, because rivers to its east flow into the Atlantic, and to its west into the Pacific. A watershed moment is, figuratively, this kind too – it’s a dividing line, something that changes the course of history, that cuts the present off from what’s come before. 

A windfall is “an unexpected, unearned, or sudden gain or advantage.” These have also been in the news, because energy shortages in Europe have led to “windfall profits” for oil companies. Windfall first referred to things that had been blown down by the wind, whether dead trees or fruit. 

To me, living in a city today, there is very little connection between the wind blowing stuff over and “unexpected advantage.” I worry about branches falling on my car when I park under a tree; when I travel to an orchard to go apple picking, I’m snobby about the ones already on the ground. When the word developed its literal and figurative senses in the 15th century, however, a windfall must indeed have been a wonderful thing. You didn’t have to cut down a tree for firewood or pick apples for pie – the wind had done your work for you.