How did Onesimus influence Cotton Mather’s support for variolation in America?

Cotton Mather’s support for variolation—a historical method of immunizing against smallpox—was directly influenced by Onesimus, an enslaved West African man living in Mather’s household.12

Onesimus introduced Mather to the practice, explaining that he had been inoculated himself in Africa. Despite facing significant public backlash and even physical threats for promoting the procedure, Mather championed the method as a scientific advancement. He documented the practice and his experiences with it, eventually sharing his account with the Royal Society of London.12

It is important to acknowledge the ethical gravity of this history: while Mather was a pioneer in advocating for this life-saving medical intervention, he was also a proponent of the institution of slavery. The knowledge that helped protect colonial American communities from smallpox originated from the lived experience and cultural traditions of an enslaved person whose own humanity was systematically denied by the society Mather helped lead.21