Quick answer: On the Shawn Ryan Show, historian Dr. Thomas Madden explained that the word "quarantine" comes from the Venetian quaranta, meaning 40, after the 40-day isolation Venice used against the plague. He also said the Venetians, as businessmen, made "contracts with God." The best-known example is Santa Maria della Salute, the domed church Venice vowed to build in 1630 if the plague ended.
Source: Shawn Ryan Show #353, Dr. Thomas Madden, clipped as a YouTube Short.
Who is Thomas Madden?
Thomas Madden is a professor of history at Saint Louis University. He writes about the medieval world, the Crusades and Venice, and is the author of Venice: A New History. He joined Shawn Ryan, the former Navy SEAL turned podcast host, for episode #353, released Nov. 2, 2026, to talk about his new book, The Fall of Republics. This clip is from the part of the conversation about Venice and the plague.
Where "quarantine" comes from
"Venice built an entire system," Madden says. In his telling, anyone shown to be sick was taken to one of the islands in the lagoon and kept there for 40 days, and newly arrived ships had their own separate island, so goods could be checked before they came into the city.
The record backs up the broad picture. In 1423 the Venetian Senate set up a permanent plague hospital on an island near the Lido, later called the Lazzaretto Vecchio. In 1468 it added a second island, the Lazzaretto Nuovo, where ships, crews and cargo suspected of carrying disease could be held for up to 40 days. That's the quaranta giorni, or 40 days, that gave English the word "quarantine."
One footnote: Venice wasn't the very first to isolate travelers. In 1377 the port of Ragusa, today's Dubrovnik, ordered 30 days of isolation for ships and 40 for travelers arriving by land. Venice, though, built the first permanent system, and other ports copied it.
"They'll make contracts with God"
"In Venice, it's very interesting because they're businessmen," Madden says. "So they'll make contracts with God." His summary of the deal: if you make this plague go away, we will give you a church.
The most famous of those deals came in the plague of 1630. On Oct. 22, 1630, Doge Nicolò Contarini publicly vowed that Venice would build a church to the Virgin Mary if the city was spared. The first stone was laid in 1631, while the plague was still raging. By the time it ended in late 1631, the city of Venice says, almost 47,000 people had died there, more than a quarter of the population.
The architect was Baldassare Longhena, and the church took decades to finish. It was consecrated on Nov. 9, 1687, five years after Longhena died.
"Holy Mary of Health"
Madden calls it "probably the most iconic church in Venice," and its great dome at the mouth of the Grand Canal does show up in a huge share of photos of the city. The name, Santa Maria della Salute, means Holy Mary of Health.
Venice still keeps its side of the bargain. Every Nov. 21, the Festa della Madonna della Salute brings a temporary bridge of boats across the Grand Canal so people can walk to the church and give thanks.
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FAQ
Where does the word "quarantine" come from? From the Venetian quaranta giorni, or "40 days," the period that ships, crews and cargo suspected of plague could be held on Venice's quarantine island.
Why was Santa Maria della Salute built? Venice vowed in October 1630 to build a church to the Virgin Mary if the city was freed from the plague. Construction began in 1631.
When was Santa Maria della Salute finished? It was consecrated on Nov. 9, 1687. The architect was Baldassare Longhena.
When is the Festa della Salute? Every year on Nov. 21.