Michael: We tend to think of global trade as a modern invention of massive cargo ships and next-day Amazon packages. But what if the most important trade deal in history involved catapulting plague-ridden corpses over a city wall? Kevin: Whoa, hold on. Catapulting corpses? That sounds less like a trade negotiation and more like a scene from a zombie apocalypse movie. What are you talking about? Michael: I’m talking about the dark engine of our interconnected world. It’s one of the central, chilling stories in the book we're diving into today: A Splendid Exchange: How Trade Shaped the World by William J. Bernstein. Kevin: A Splendid Exchange. That title sounds so… civilized. Not very corpse-catapulty. Michael: Exactly! And that's the paradox at the heart of the book. What's fascinating is that Bernstein isn't a traditional historian; he's a financial theorist and a trained neurologist. So he approaches this entire history not just as a series of economic transactions, but as a fundamental, almost biological, human impulse. Kevin: A neurologist? Okay, that actually makes a lot of sense. It’s not just about spreadsheets and supply chains; it’s about our brains being wired to, as Adam Smith famously put it, "truck, barter, and exchange one thing for another." It's in our DNA. Michael: It is. Bernstein argues that for most of human history, societies have had three options to get what they don't have: make it, raid it, or trade for it. And trade, for all its flaws, has been the most powerful engine of progress. But that progress has always come with a very, very steep price.

Michael: And that price is the first big idea we need to tackle. We love the 'splendid' part of the exchange, but we often ignore the brutal reality it was built on. Let's take the spice trade, for example. We picture these romantic, exotic markets filled with fragrant spices… but the reality was something else entirely. Kevin: Yeah, my image is basically the opening scene of Disney's Aladdin. Bustling markets, vibrant colors, maybe a friendly merchant trying to sell you some cinnamon. I'm guessing that's not quite accurate. Michael: Not even close. For that, we have to look at the story of Vasco da Gama, the Portuguese explorer who first sailed from Europe to India in 1498. When he arrived in the port of Calicut, a major hub for the spice trade, the Portuguese were completely out of their depth. They brought trade goods they thought were valuable—woolen cloth, hats, strings of coral beads. Kevin: Let me guess, the Indians were not impressed. Michael: The local merchants basically laughed at them. They were used to dealing in gold, silver, and high-quality textiles. The zamorin, the ruler of Calicut, was shown these pathetic European goods and was deeply unimpressed. Da Gama left with a tiny amount of spice and a massive amount of humiliation. Kevin: Okay, so a failed business trip. Embarrassing, but it happens. Michael: Ah, but this is where the story turns. Da Gama returned to Portugal, and when he came back to India a few years later, he wasn't just a trader. He was a commander of a war fleet. He understood that Portugal couldn't compete on the quality of its goods. So, they would compete with the quality of their cannons. Kevin: So if you can't win the deal, you just… blow up the competition? Michael: Precisely. On his second voyage, to send a message, da Gama captured a ship returning from Mecca, filled with hundreds of Muslim pilgrims, including women and children. He locked them below deck and set the ship on fire, killing nearly everyone on board. Kevin: Hold on. He burned a pilgrim ship? That’s not trade. That's an act of terrorism to force a market open. Michael: It was. And it was a calculated one. The Portuguese established a system they called cartaz. Any ship that wanted to trade in the Indian Ocean had to buy a license—a cartaz—from the Portuguese. If you were caught without one, your ship was seized, your cargo confiscated, and your crew was often killed. It was a protection racket on a global scale. Kevin: So the 'splendid exchange' was basically, "Trade with us, or die." That completely reframes the Age of Discovery. But why? Why were spices so important that they would resort to this level of brutality? Were they just trying to make their food taste better? Michael: That’s the common misconception. Yes, pepper was a status symbol, but it was more than that. In medieval Europe, a wealthy person was called a "pepper sack." A bag of pepper was often worth more than a human life. Spices were the ultimate luxury good, a way to display immense wealth and power. Kevin: Like a medieval billionaire showing up in a Bugatti. Michael: Exactly. And Europe had a massive trade deficit with the East. They wanted spices, silk, and porcelain, but the East didn't want much of what Europe produced. So, for centuries, the only way for Europeans, particularly the Venetians and Genoese, to balance the books was to pay in gold and silver, or… to trade in something else the Muslim world desperately wanted. Kevin: What was that? Michael: Slaves. For a long time, the Italian city-states funded their spice purchases by selling slaves, often from the Black Sea region, to the Mamluk Sultanate in Egypt. It’s this incredibly dark, interconnected economy where the desire for nutmeg in a European court is directly linked to the slave markets of the East. Kevin: Wow. So the visible cargo was spices, but the hidden currency was violence and human lives. That’s a much darker story than the one we usually get.

Kevin: Okay, so the visible cargo was spices, and the hidden currency was often violence and slavery. But the book argues the most world-changing cargo was something else entirely, right? Something invisible. Michael: Precisely. The most transformative things traded weren't always on the manifest. Bernstein makes a powerful case—and it's one that some critics of the book find a bit too deterministic—that disease was the ultimate world-shaper. And the story of the Black Death is the ultimate, horrifying case study of this. Kevin: I think most people know the Black Death was bad, but I don't think they connect it directly to… a business deal gone wrong. Michael: Well, it starts at a trading post. In 1346, the city of Kaffa, on the Crimean peninsula, was a bustling port run by Genoese merchants from Italy. It was the western end of the Silk Road, a vital link between Europe and the Mongol Empire. But the Mongols, who controlled the surrounding lands, started to feel a bit of seller's regret. They saw how rich the Genoese were getting and decided they wanted the city for themselves. So they laid siege to it. Kevin: A classic business dispute resolution technique. Michael: Indeed. But during the siege, a catastrophe struck the Mongol army. A mysterious illness swept through their camp, killing thousands. They were being wiped out. The siege was failing. In a final, desperate act of malice, the Mongol commander ordered his men to load the plague-infected corpses of their own soldiers onto their catapults. Kevin: No. You're kidding. Michael: He wasn't. They launched the bodies over the walls and into the besieged city of Kaffa. One chronicler at the time wrote that it "seemed like mountains of dead were thrown into the city." The stench was unbearable, but the real damage was invisible. The plague had breached the walls. Kevin: And the Genoese traders inside were trapped with it. Michael: Exactly. They started dying in droves. The survivors did the only thing they could think of: they fled. They scrambled onto their trading galleys and set sail for home, hoping to outrun the pestilence. But they didn't know that the plague wasn't just in the people. It was in the rats in their cargo hold, and more importantly, in the fleas on those rats. Kevin: Oh man. They were carrying the apocalypse with them. Michael: They were. Bernstein explains the biology beautifully. The plague bacillus, Yersinia pestis, has a perfect delivery system. It lives in rodents. The black rat, Rattus rattus, loves living with humans. And its preferred parasite, the oriental rat flea, has a unique digestive feature. When the flea bites an infected rat, the plague bacteria multiply in its gut, blocking it. The flea becomes ravenously hungry, but it can't digest. So it jumps from host to host, frantically biting and regurgitating a slurry of plague bacteria into each new victim. Kevin: That is horrifyingly efficient. So these ships, filled with desperate people and infected rats, sail back to Italy? Michael: They do. In October 1347, twelve Genoese galleys docked in Messina, Sicily. The locals saw sick and dying men on board and tried to turn them away, but it was too late. The rats scurried down the mooring ropes. The fleas found new hosts. Within days, Messina was a plague pit. From there, the disease spread like wildfire along the very trade routes that had made Italy rich. Venice, Genoa, Florence—all the great trading hubs became epicenters of death. Kevin: Wow. So the very trade routes that were the source of their wealth became the superhighways for their own destruction. It’s like a Greek tragedy. And people at the time had no idea what was causing it, right? They must have been terrified. Michael: Utterly. They blamed "miasma" or bad air. They blamed planetary alignments. And tragically, they blamed their neighbors. Across Europe, communities turned on and massacred Jewish populations, accusing them of poisoning the wells. Groups of flagellants roamed the countryside, whipping themselves to atone for the sins they believed had brought God's wrath. It was total societal breakdown, all because a microscopic passenger hitched a ride on a trade route.

Michael: And when you put those two stories together—the violent birth of the spice trade and the plague's journey along the Silk Road—you get the core message of A Splendid Exchange. Trade is this incredible engine of progress. It brought paper, the compass, new foods, and new ideas across the world. It connected humanity. Kevin: But that very connection is its greatest vulnerability. The same pathways that carry silk and spices can carry cannons and microbes. The splendor and the exchange are inseparable from the violence and the contagion. Michael: Exactly. Bernstein's ultimate point is that globalization isn't new. It's an ancient force. And its risks have always been as profound as its rewards. The fall of the Roman Empire, the rise of Europe, the colonization of the Americas—he argues you can't understand any of these without understanding the history of trade and its unseen consequences. Kevin: It really makes you look at a container ship stuck in the Suez Canal or a microchip shortage today in a completely different light. We're still living in the world that these ancient trade routes built, with all the same fundamental vulnerabilities. It really makes you wonder, what are the 'invisible passengers' we're trading today that we're not even aware of? Michael: That's a powerful question. It could be a new financial crisis, a piece of viral misinformation, or a future pandemic. The mechanisms are faster, but the principle is the same. We'd love to hear what our listeners think. What are the modern equivalents of the Black Death riding on our global supply chains? Find us on our socials and share your thoughts. Kevin: It’s a sobering thought to end on, but a necessary one. This book is a fantastic, if sometimes terrifying, reminder that history isn't just something that happened. It's the operating system we're all still running on. Michael: This is Aibrary, signing off.