The price of a captive in Senegambia rose tenfold

The price paid for a captive in Senegambia multiplied by ten between 1680 and 1830, the stretch in which the Atlantic trade did its heaviest damage to African societies. Demand from the plantation colonies drove the rise. Buyers in Saint-Domingue, Jamaica, Brazil and Virginia wanted more people every year, and competition among European carriers passed straight back down the chain to the coast. African rulers and merchants took large profits, paid in textiles, hardware, firearms and spirits. Guns are the item to watch. A state that sold captives could buy weapons, weapons made it easier to take more captives, and neighbours had to enter the trade or be sold into it. Across a hundred and fifty years that loop reorganised the politics of a whole region. A rising price is normally read as a market signal. It is also a measure of how far the traffic had been built into the way West African states survived.

In 1757 an enslaved man named Medor went before the court at Cap Francais in Saint Domingue and confessed without being compelled. He said that he and many others used magical powders to persuade owners to grant them their freedom. His statement opened the enormous investigation that became the Makandal affair. Trevor Burnard and John Garrigus have since tracked the timing and geography of the deaths blamed on poison that year and argue that mycotoxins in spoiled flour, during a wartime blockade, are the likelier cause. On that reading Medor and the others who confessed to using poison and spells to tame their owners may genuinely have believed their taming had killed by accident. The same pattern turns up far away. In Suriname, Clarinda and Nero insisted that the mixture Nero made from bush herbs was meant to calm Clarinda's mistress, and Clarinda was alarmed when the woman fell ill and died.

Felix Darfour was born in western Sudan, taken to France by an officer of the Egyptian expedition, educated and married there, and settled in Haiti in 1818, where the constitution granted nationality to any African who came to live in the country. He founded a newspaper, L'Eclaireur, later renamed L'Avertisseur. On 30 August 1822 a message from him was read to the Chamber of Representatives. It said that Jean-Pierre Boyer favoured foreigners with a monopoly of commerce, that Haitian fortunes could not rise under him, and that the president gave advantages only to men of colour while refusing blacks instruction in order to prove them naturally unfit to govern. Boyer ordered him tried by a military commission on the morning of 31 August. He was sentenced the same day and shot on 2 September in front of the people and the army. Darfour was a civilian tried by soldiers, and the petition itself never entered the case file.

Between 1677 and 1682 an investigation at the court of Louis XIV drew in close to four hundred suspects. At its centre was a circle of noblewomen who commissioned love magic from a sorceress in Paris. Investigators then turned up something else. The same sorceress was said to have sold deadly poisons made from toads to heirs impatient for their inheritances, and to have had charms consecrated by rogue priests. The French script of the moment held that women used potions to make men love them, an inversion of order that frightened the powerful. The affair produced a royal edict in 1682 that criminalised pretended magic, punished superstitious use of sacred objects and prayers, and tightened the sale of arsenic and mercury sublimate. Its effect in France was to cut accusations of sorcery by renaming the accused as false sorcerers or poisoners. Forty two years later that edict was extended to the French islands of the Caribbean.