Sir Isaac Newton’s Prescription for Plague? Toad Vomit Lozenges

Handwritten notes detailing the British polymath’s unsavory treatment are now up for auction

Portrait of Isaac Newton
A portrait of scientist Isaac Newton, who developed a toad vomit–based cure for the bubonic plague Godfrey Kneller via Wikimedia Commons under CC BY-SA 3.0

If someone told you that Sir Isaac Newton—the great mind responsible for the discovery of calculus and fundamental laws of physics—had also developed a remedy for the bubonic plague, you’d be forgiven for assuming it might be worth a shot. You would, however, be in for an unwelcome surprise.

In 1665, when Newton was a student at the University of Cambridge’s Trinity College, the school temporarily shuttered due to the Great Plague of London. This outbreak of bubonic plague lasted until 1666 and killed an estimated 100,000 people—roughly a quarter of the city’s population, according to Encyclopedia Britannica.

As the plague raged through England, Newton quarantined himself at Woolsthorpe Manor, his family estate in Lincolnshire. In the two years he spent isolated at Woolsthorpe, Newton, to put it mildly, got some good work done.

His period of social isolation was rife with experiments on gravity—including that whole business with the apple tree—and breakthroughs in mathematics, physics and optics. But as Thomas Levenson writes for the New Yorker, Newton’s achievements during the epidemic can’t be attributed solely to the magic of solitude, as is sometimes suggested, but rather to the fact that he was Isaac Newton.

When Newton returned to school in 1667, he threw himself into the medical works of Belgian physician Jan Baptist van Helmont, according to a statement from the Bonhams auction house. While working through van Helmont’s book on the plague, De Peste, the young scientist penned a proposed plague cure in his handwritten notes. Now, two pages of these previously unpublished scribblings are up for sale in Bonhams’ June manuscripts auction.

The British polymath’s plague remedy dates to 1669, which was admittedly a long time ago—but just how bad could it be?

The first step in the cure is hanging a toad upside down in a chimney for three days. You’ll know your toad is ready when it pukes and dies; be careful to collect all the vomit, which Newton describes as containing “earth with various insects in it.”

Next, grind the toad into a powder and mix it with the vomit until you’ve formed several lozenges. Finally, place your toad vomit lozenges “about the affected area.”

Isaac Newton's notes
A handwritten manuscript penned by Isaac Newton containing his notes on reading Jan Baptist van Helmont's De Peste. The notes are written in Latin with some Greek and alchemical symbols. Courtesy of Bonhams

Newton stipulated that this was his “best” cure, suggesting it “drove away the contagion and drew out the poison,” according to Bonhams. The rest of Newton’s plague bullpen was populated by amulets of “hyacynth” (possibly the stone jacinth), sapphire and amber, writes the auction house in the lot’s description.

In the statement, Bonhams Book and Manuscript Specialist Darren Sutherland says, “Newton’s notes are essentially his take on the De Peste, including theories on its causes and speculation about cures. They represent the only significant writings on the subject by the world’s greatest scientific mind that we have been able to trace.”

The notebook’s pages also include more enduring recommendations, including the common sense observation that “places infected with the plague are to be avoided.” In one instance, Newton describes the case of a man who touched pestilent papyrus, immediately felt a pain like a pricking needle, and developed a pestilent ulcer in the forefinger, and died in two days,” according to Bonhams.

Sutherland notes that van Helmont, who also dabbled in philosophy, mysticism and chemistry, was “a great influence on Newton.” The Belgian physician wrote De Peste following his experiences in Antwerp during an outbreak of plague in 1605.

Newton’s reflections on De Peste have never previously appeared in collections of his works, reports Alison Flood for the Guardian. They have changed hands among private collectors since being sold by Newton’s descendants in 1936.

“There was never much interest in his ‘other’ writings until recently,” Sutherland tells the Guardian. “So it really is a case of cometh the hour, cometh the man—with his remedies to ward off a virus that’s causing a pandemic.”

The pair of unpublished, handwritten pages is up for auction alongside such items as a signed draft of the closing lines of Walt Whitman’s last poem, “A Thought of Columbus,” and Mark Twain’s meditations on medicine. Bonhams estimates that Newton’s reflections on De Peste will fetch between $80,000 and $120,000.

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