... having been breathed out

Boston's status as one of the key ports in the colonies left the city vulnerable to disease. On April 21, 1721, the HMS Seahorse sailed into Boston Harbor from Barbados. A month later, Cotton Mather logged in his journal, "The grievous calamity of the smallpox has now entered the town." One thousand Bostonians, nearly 10 percent of the town, fled to the countryside to escape the judgment of the Almighty.

Fifteen years prior, Mather had asked Onesimus[, an enslaved West African man Mathers's congregation had bought for him,] one of the standard questions that Boston slaveholders asked new house slaves—Have you had smallpox? "Yes and no," Onesimus answered. 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. Racist European scientists at first refused to recognize that African physicians could have made such advances. Indeed, it would take several decades and many more deaths before British physician Edward Jenner, the so-called father of immunology, validated inoculation.

Cotton Mather, however, became an early believer when he read an essay on inoculation in the Royal Society's Philosophical Transactions in 1714. He then interviewed Africans around Boston to be sure. Sharing their inoculation stories, they gave him a window into the intellectual culture of West Africa. He had trouble grasping it, instead complaining about how "brokenly and blunderingly and like Idiots they tell the Story."

On June 6, 1721, Mather calmly composed an "Address to the Physicians of Boston," respectfully requesting that they consider inoculation. If anyone had the credibility to suggest something so new in a time of peril it was Cotton Mather, the first American-born fellow in the London's Royal Society, which was still headed by Isaac Newton. Mather had released fifteen to twenty books and pamphlets a year since the 1690s, and he was nearing his mammoth career total of 388—probably more than the rest of his entire generation of New England ministers combined.

The only doctor who responded to Mather was Zabadiel Boylston, President John Adams's great-uncle. When Boylston announced his successful inoculation of his six-year-old son and two enslaved Africans on July 15, 1721, area doctors and councilmen were horrified. It made no sense that people should inject themselves with a disease to save themselves from the disease. Boston's only holder of a medical degree, a physician pressing to maintain his professional legitimacy, fanned the city's flames of fear. Dr. William Douglass concocted a conspiracy theory, saying there was a grand plot afoot among African people, who had agreed to kill their masters by convincing them to be inoculated. "There is not a Race of Men on Earth more False Liars" than Africans, Douglass barked.