Revisiting a Young Isaac Newton

Isaac Newton is typically portrayed as a solitary scientist with intense focus who was obsessed with power and deeply egotistical. But a new book by Caltech historians Jed Buchwald and Mordechai Feingold takes a deeper look at Newton's life in the two decades leading up to the 1687 publication of his groundbreaking text, Principia Mathematica, when he was 44. Utilizing newly digitized scans of Newton's early writings, Buchwald and Feingold uncover a novel portrait of the young polymath as a curious and social scholar whose interests were often fleeting.

"What struck me is the extent to which Newton was not always who he eventually came to be," says Feingold, the Kate Van Nuys Page Professor of the History of Science and the Humanities. "He's certainly a towering intellectual, a genius, if you want to use this cliche, but he's far more complex and interesting than many accounts portray. He could be social and collegial and was a universal scholar in a sense, even though he lacked grounding in many things."

Buchwald and Feingold's book, The Winding Trail to Newton's Principia Mathematica, was published on September 29 by Princeton University Press.

The Principia is the first published work to establish the mathematical foundation for the theory of classical mechanics by explaining the fundamental physical laws governing motion and gravity. In addition to challenging the standard portrait of Newton in his early career, the authors also posit that that the foundation of the axioms of the Principia—Newton's Three Laws of Motion—were commonplaces ideas of the time that Newton restructured.

In fact, the authors note, prior to a pivotal visit from astronomer and mathematician Edmond Halley in 1684, Newton engaged only sporadically with celestial mechanics, or the study of the movement of astronomical objects, including the gravitational pull they can have on each other. During their discussions, Halley asked Newton a question about planetary orbits and set the Principia in motion. (Halley later used Newton's "new" laws to determine the orbits of comets and predicted the return of what would be later known as Halley's Comet.)

"The Principia does not emerge in his head out of the sky," says Buchwald, the Doris and Henry Dreyfuss Professor of History. "We've given a whole new view of how the route to the Principia evolved."

Buchwald and Feingold have been friends and collaborators since they first joined the Caltech faculty in the early 2000s. Longtime Newtonian scholars, they published their first book together in 2012, Newton and the Origin of Civilization. That book examined how Newton applied his unique ways of thinking, such as reading archaic texts through the lens of astronomy, to create a drastically revised timeline for ancient civilizations, which was revealed in 1728, a year after his death, in The Chronology of Ancient Kingdoms Amended.

Along with a former student, Andrej Svorenčík (MS '08), Feingold spent more than a decade tracing first-edition versions of the Principia around the world. In a survey published in 2020, they described how they had unearthed nearly 200 previously uncounted copies.

"At some point, maybe about five years ago, I started bugging Jed again about Newton," Feingold recalls. "I had been doubting for many years the traditional story about how Newton got to the start of his scientific career and what influenced him, and I told Jed, 'There is more to be done.'"

Recently digitized files for many of Newton's early manuscripts made it possible for Buchwald and Feingold to interrogate his younger years in more detail. The basis for the book was born.

"Both of us had seen the manuscripts before, but even with your magnifying glass, you can't always see everything," Buchwald says. "These marvelous digitizations were done at such high resolution that you could pull things up that people had not seen before, such as small but meaningful parts of diagrams that reveal important elements of Newton's constructions. There's been a lot of good scholarship over the many decades about Newton, even some 200 years old, but it's all been overshadowed by the existence of the immensely influential Principia."

Feingold says that approaching the manuscripts from a different perspective allowed them to gain novel insights.

"We were not hamstrung by certain preconceptions about what Newton should be doing, philosophical or otherwise," Feingold explains. "I think this enabled us to take a new bird's-eye view and either discover new things or revise notions that have been stated before."

The two corresponded with other experts—including Niccolò Guicciardini, who Buchwald calls the "greatest living historian of Newton's mathematics"—and met with each other often for an exchange of views as they researched and wrote the book. "It's this kind of daily interaction, querying the text and querying each other, that enabled us to reach the goal of charting a unique view of Newton's path to the Principia."

Buchwald says that one of their most surprising findings is that the groundwork for all the mechanics outlined in Newton's Principia was floating around in scientific conversations and writings of the time.

"We can see it in the works of other people like mathematicians John Wallis, Christopher Wren, and others, utilized in various different ways," he says. "But the principles for Newton's laws of motion become locked and concrete in a different way when brought together with the mathematical and experimental peculiarities that characterize him. You can't say that the Principia invented a completely novel mechanics."

Buchwald and Feingold hope their findings draw interest from scholars and the public alike both now and in the future.

"It would be nice if more attention could be turned, particularly in the history of science, toward trying to understand people as who they were, what they did, and the way in which they worked things," Buchwald says.