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Onesimus (?-?)

Onesimus was an enslaved man from Africa whose knowledge of smallpox inoculation was instrumental in the tradition being taken up in the United States. He was purchased as a slave for Cotton Mather, a Puritan church minister in Boston, by Mather’s congregation in 1706. For his keen interests in science and medicine Mather had been elected as an honorary member of London’s Royal Society in 1713. In a letter to the society sent in 1716, he records how Onesimus revealed to him a method of smallpox inoculation that he had undergone while still in Africa - he had the scar on his arm to confirm it. In 1721 Mather would use this knowledge to promote - against sometimes violent opposition - mass inoculation against smallpox when an epidemic of the disease struck Boston.

Because of his role in this act of knowledge transfer, Onesimus has a significant place in the history of smallpox inoculation. For an enslaved man, such a profile is unusual. The lives and voices of the vast majority of enslaved men, women and children are effectively lost to history - such was the inhumane nature of slavery. Alas, very little is known of Onesimus’s life. He remains a fleeting figure in the historical record.

Mather may have acted on Onesimus’s experience and knowledge of smallpox, but Onesimus remained a slave in the household and one that Mather eventually turned against. After failing to convert him to Christianity and considering him to be increasingly rebellious, Mather signed a conditional document in 1721 that allowed Onesimus to purchase his freedom - Onesimus having earlier given money toward the purchase of another black youth, Obadiah, to take his place. He also continued to do chores for the Mather family when required.

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M Best, D Neuhauser, and L Slavin, '"Cotton Mather, you dog, dam you! I'll inoculate you with this; with a pox to you'': smallpox inoculation, Boston, 1721' Quality and Safety in Healthcare, 13/1 (2004) pp 82-83

T H Brown, ‘The African connection : Cotton Mather and the Boston smallpox epidemic of 1721-1722’, Journal of the American Medical Association, 260 (1988) pp 2247-2249

K Silverman, The Life and Times of Cotton Mather (New York: Harper & Row, 1984)



A sudden widespread occurance of an infection with high numbers of people affected.