The Rational Optimist (P.S.)

by Matt Ridley

Amalfi, Pisa, and above all Genoa began to flourish on the back of the Maghribi trade. It was a Pisan trader living in north Africa, Fibonacci, who brought Indian–Arabic decimals, fractions and the calculation of interest to Europe’s notice in his book Liber Abaci, published in 1202. Genoa’s trade with North Africa doubled after an agreement for the protection of merchants was reached in 1161, and by 1293 the city’s trade exceeded the entire revenue of the king of France. Lucca acquired a strong position in the silk trade and then in banking. Florence became wealthy through weaving wool and silk. Milan, gateway to the Alpine passes, flourished as a market town. And Venice, long independent in the safety of its lagoon, gradually became the epitome of the trading state. Despite competing and often warring with each other, republican city states, run by merchants, not only took care not to tax or regulate trade into extinction, but did everything they could to encourage it: in Venice, for example, the government built and leased ships and arranged convoys. Italy’s prosperity