In the last years before the French Revolution, Nantes looked like a boomtown. Arthur Young, passing through in 1788, took its fresh construction as a sign of prosperity that never lies. French slaving had been run out of the port for close to a century, and by 1789 its merchants were committing something near 10 million livres each year to the traffic.

Stein argues the appearance misleads. Behind the busy port most traders found the business hard going, squeezed by conditions in France, in the colonies, and on the African coast. A few did assemble enormous fortunes almost at once, and that possibility kept drawing capital in.

Measured soberly, returns across the old regime's last ten years ran about level with what an investor could expect from land or from buying an office. What set slaving apart was not its ordinary yield but its long odds on sudden, immense gain.