He explained how in Africa before his enslavement, a tiny amount of pus from a smallpox victim had been scraped into his skin with a thorn, following a practice hundreds of years old that resulted in building up healthy recipients’ immunities to the disease. This form of inoculation—a precursor to modern vaccination—was an innovative practice that prevented untold numbers of deaths in West Africa and on disease-ridden slave ships to ports throughout the Atlantic.
