Marx's proletarian sells labour power as a commodity because nothing else remains to sell; the Caribbean plantation slave was himself bought and sold. Mintz asks how far apart those two categories stand once particular histories are examined. He divides four centuries of Caribbean plantation history into five phases and shows that unmixed slavery was rare and short-lived: enslaved Africans worked beside commended Indians, European indentured servants, Chinese contract labourers in Cuba, and Puerto Ricans declared vagrant by legislation in 1809. The core of the argument concerns provision grounds. Planters granted slaves marginal land and free days to feed themselves, and slaves used them to work unsupervised, in groups of their own choosing, raising surpluses they carried to Sunday markets that fed much of the free population and circulated a fifth of Jamaica's coin. Mintz treats this breach in the system as evidence that categories built for European capitalism need reworking for a world economy that produced both kinds of worker.