Mather’s son, Cotton, was even more historically poignant. Cotton Mather followed in his father’s footsteps in the church, becoming an assistant pastor to his father at the Second Church before eventually gaining full pastoral responsibility in 1685. Mather is remembered most for his vehement support of the Salem witch trials and even wrote two books on witchcraft that no doubt fanned the fires.
However, Mather Jr. was able to affect history in a more positive way, thanks to his slave Onesimus. Onesimus was an African slave gifted to Cotton Mather by his church congregation in 1706, four years after the most recent bout of Boston’s smallpox problem. Upon learning of this, Onesimus told Cotton of a procedure he had in Africa that placed a small bit of the disease into a person’s body that made them immune to the smallpox disease.
Mather freed Onesimus conditionally in 1716, but it wasn’t until five years later that he put the knowledge Onesimus had given him to use. Mather contacted people like Dr. John Woodward of Gresham College in London, as well as local authorities and doctors, relaying the knowledge of innovations that Onesimus had given him. He finally convinced Dr. Zabdiel Boylston to test out the smallpox vaccines during an outbreak of smallpox in Boston in late summer of 1721. Boylston’s tests proved successful, and the city was smallpox-free by February 1722.