Today’s presidential candidates are playing recklessly with free trade, alliances and immigration. They are pushing the misguided notion that high trade barriers will restore jobs and prosperity to the middle class, and scorning old alliances and new immigrants. These protectionist and nativist ideas aren’t new; they’re as old as the Greeks. Athens tried them but it created international disorder and the opposite of the desired result.

While nationalism will always be fodder for politicians, today’s leaders need to understand the consequences. Athens learned the hard way. Here are the lessons:

The story begins about 2,500 years ago with an alliance between Athens and the Greek city-states of the Aegean. Historians usually call it an empire, but it was more like a cross between the European Union and the Warsaw Pact. It was meant to protect Greece against Persia and it succeeded so well that it left some allies complaining it had turned into a protection racket in which they were bullied into playing along but got nothing in return. Athens didn’t allow allied exits and backed up its position with force.

At first, things worked smoothly. Athens slowly turned the alliance into a common market in which Athenian coins, weights and measures became the norm, a kind of ancient euro. Athens’s free-trade zone fostered prosperity, democracy and the soaring confidence that built the Parthenon and fired the Golden Age of Greece.

Read the full article at the Wall Street Journal: How Anti-Trade Nativism Wrecked the Ancient Greeks