Onesimus Mather and the Origins of Inoculation in Boston
By: Rowan Wheeler
In 1721, Boston was in the middle of a mass exodus. That summer, hundreds of Bostonians fled to smaller villages and towns to escape the threat of smallpox. That year’s pandemic would wipe out 14% of Boston’s population. Meanwhile, minister Cotton Mather and Dr. William Douglass, perhaps Boston’s foremost physician, debated if they could trust the medical advice of enslaved people to save lives. Ultimately, Onesimus Mather, enslaved by Cotton Mather, provided the evidence needed to successfully perform the first American inoculation campaign.
Prior to 1721, slave ships from Africa entering Boston Harbor had long been vectors of disease because of their abysmal conditions. Smallpox death rates would have made such transmissions even higher if it weren’t for an important practice in many parts of Africa: inoculations. With smallpox outbreaks common in colonial New England, some notices of slave ships coming into Boston promoted their human cargo as immune to smallpox. While slaveholders embraced the immunity as a way to avoid losing their property to the illness, few seemed interested in inquiring about this seemingly life-saving process. Unlike his peers, when the Puritan minister of Boston’s North Church, Cotton Mather, was gifted an enslaved African man by his congregation in 1707, he immediately asked if the man was immune to smallpox. Onesimus, as Mather called him, gave a confusing answer:
“Onesimus, ‘a pretty Intelligent Fellow’, answered, both, Yes, and No; and then told me, that he had undergone an Operation, which had given him something of the Small-Pox & would forever preserve him from it; adding that it was often used among the Guramantese, & whoever had the Courage to use it, was forever free from the fear of Contagion.”
When Mather saw reports of similar procedures being used in Turkey years later, he sent a letter describing Onesimus’s knowledge to the Royal Society of Medicine in London in support of Turkish claims of inoculation’s efficacy. In his 1716 letter, Mather emphasized how Africans were at the forefront of such practices, stating “Many months before I met with any intimations of treating the smallpox with the method of inoculation, anywhere in Europe; I had from a servant of my own an account of its being practised in Africa… he showed me in his arm the scar which it had left upon him.” Mather’s insistence of Onesimus’s intelligence and the physical evidence of his scar portrayed Onesimus as a valid source of medical knowledge. Although primarily a spiritual leader, Mather also considered himself a scientist and was eager to prove to European scientific elites that they did not have a monopoly on medical expertise.
While Mather used Onesimus’s firsthand accounts to his advantage in correspondence with European authorities, the two were simultaneously parting ways. Mather complained in his diary of how Onesimus refused to convert to Christianity, and wrote in August of 1716 that he “proves wicked, and grows useless, froward [ungovernable], and immoregerous [rebellious].” As a result, Mather freed Onesimus, who indirectly purchased his freedom by providing “a Summ, towards the purchase of a Negro-Lad” so that Mather could buy another enslaved person to replace him. However, the contract securing Onesimus’s freedom stipulated that he would continue to do some of Mather’s chores for free, including shoveling snow and chopping wood for fuel. Onesimus continued to live in Boston, and according to Mather was married with children, though specifics on any names and dates for such individuals are elusive.
While Mather did not trust Onesimus to be obedient, his actions proved that he continued to trust him as a source of medical knowledge. As the 1721 smallpox pandemic raged in Boston, Mather wrote to Boston’s physicians, urging them to follow Onesimus’s outlined procedure. They resisted, as did some outraged citizens. An explosive was thrown in the front window of Mather’s house, no doubt conjuring memories for him of the fire that destroyed his childhood home in 1676.
Further fuel against Mather came from James Franklin, the cousin of Benjamin Franklin. Franklin took to the press and started the New England Courant newspaper to dispute Mather’s claims. In it his publications, Franklin called on Dr. William Douglass, who satirized Mather in a malevolent fashion. Instead of assisting Bostonians, Douglass suggested that colonists could alternatively use inoculations to spread smallpox in local indigenous tribes.
Only one doctor listened and heeded Mather’s arguments: Zabdiel Boylston. Boylston interviewed other enslaved people in Boston and found that they had similar experiences to Onesimus and that inoculation was a common practice within the Black community of Boston. After testing the procedure on his young son and on two of his enslaved persons, Jack and Moll, Boylston began inoculations in earnest. In putting Onesimus’s insights into practice, Boylston relied on Black bodies to provide the evidence that inoculation worked.
The criticism of Boylston and Mather relied on anti-Black sentiment. Mather based his arguments on Onesimus’s testimony, but as a result, some Bostonians believed that an enslaved person advocating for such a risky procedure must be doing so to sabotage them. Dr. Douglass criticized Mather’s suggestions, claiming that trusting only word-of-mouth accounts without scientific trials was dangerous, especially when that knowledge came from enslaved people he personally deemed incapable of rational thought.
Mather’s arguments for inoculation also had racist roots. In a treatise he wrote with Boylston after the pandemic, he claimed that “[t]hus in Africa, where the Poor Creatures [die] of the Small-Pox like Rotten Sheep, a Merciful GOD has taught them an Infallible Preservative.” Mather saw Africans’ use of inoculation as divine mercy from God on a people without knowledge or skill, not a practice of their own creation. By framing inoculation as divinely gifted knowledge from God, Mather hoped to convince white Bostonians the practice was legitimate, not sabotage. Portraying Onesimus as a “benign [recipient] of God’s universal grace” also furthered Mather’s claims of the benefits of converting enslaved Africans to Christianity. Ironically, Mather made these claims despite his inability to convert Onesimus.
While records of Onesimus after he freed himself from slavery are scarce, Boylston’s 242 recorded inoculations proved Onesimus and other Africans had provided valuable knowledge. Only six of Boylston’s patients died, the 2.5% death rate much lower than the 14% death rate of the larger Boston population. Although many Bostonians condemned Mather and Boylston during the pandemic, afterwards inoculation became a common New England medical practice. Onesimus’s testimony created a path to inoculation, and later vaccines, in America.
Rowan was the 2020 Summer Intern for the Paul Revere Memorial Association
Similar to vaccination, inoculations usually consist of taking the pus from someone who is infected and rubbing it into a cut made on a healthy person, deliberately infecting them. Once the infected material is introduced into the body, the healthy person will hopefully develop a mild case, becoming inoculated. The process of vaccination was invented by Edward Jenner in 1796. While in vaccinations, a weakened version of the pathogen is introduced, the pathogen itself is used to infect in inoculations.
 G. L. Kittredge, ‘Introduction’ to Increase Mather … and Cotton Mather, Sentiments on the Small Pox Inoculated (Cleveland, 1921), 4.
 Boyleston, Arthur. The origins of inoculation. Journal of the Royal Society of Medicine, 2012 Jul; 105(7): 309–313. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3407399/
 Diary of Cotton Mather for 31 August, 1716.
 Memo outlining terms of freedom. Cotton Mather, undated and unidentified letters and fragments, Mather Family Papers, 1613-1819. Box 5, Folder i. American Antiquarian Society.
 For a thorough dive into Onesimus’s potential appearances in Boston records, see J.L. Bell, “Onesimus Mather in Freedom.” http://boston1775.blogspot.com/2020/04/onesimus-mather-in-freedom.html
 The house built in place of Mather’s childhood home was constructed in 1680, and is now known as the Paul Revere House after its most famous resident.
 Wisecup, Kelly. “African Testimony, Dangerous Communications, and Colonial Medical Knowledge in the 1721 Boston Inoculation Controversy.” In Medical Encounters: Knowledge and Identity in Early American Literatures, 97-126. University of Massachusetts Press, 2013. Accessed July 12, 2020. www.jstor.org/stable/j.ctt5vkb14.7. 118.
 Mather, Cotton. Some Account of What Is Said of Inoculating or Transplanting the Small Pox, by the Learned Dr. Emanuel Timonius, and Jacobus Pylarinus: With Some Remarks Thereon. Boston, 1721. Early American Imprints. 9. https://curiosity.lib.harvard.edu/contagion/catalog/36-990023289740203941
 Minardi, Margot. “The Boston Inoculation Controversy of 1721-1722: An Incident in the History of Race.” The William and Mary Quarterly, Third Series, 61, no. 1 (2004): 47-76. Accessed July 12, 2020. doi:10.2307/3491675. 66.