Caltech historians use newly digitized manuscripts to portray the young Newton as a sociable scholar

The method is a second look. Buchwald and Feingold had worked with Newton's early manuscripts before. This time they had much sharper images ^[10]. "Both of us had seen the manuscripts before, but even with your magnifying glass, you can't always see everything," Buchwald said ^[9]. He said the digitizations let them "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" ^[10].

That evidence fits the book's argument about how the mathematics came together. A recovered piece of a diagram shows how a construction was built, and anyone with the same images can check the reading. If celestial mechanics was only an occasional interest until Halley's 1684 visit ^[5], the Principia followed that visit by three years ^[1]. On that timeline, about 17 of the 20 years the book covers pass before Halley asked the question that started it ^[2]. "The Principia does not emerge in his head out of the sky," Buchwald said ^[6].

The sociable Newton is a separate claim. The standard portrait is of a solitary man with intense focus, obsessed with power and deeply egotistical ^[15]. The book's Newton is a curious, social scholar whose interests were often fleeting ^[2]. He was about 24 at the start of the period and 44 at its end ^[3]. "What struck me is the extent to which Newton was not always who he eventually came to be," Feingold said ^[7]. "He could be social and collegial and was a universal scholar in a sense, even though he lacked grounding in many things," he said ^[8].

The published account quotes only the two authors. It does not say which letters, notebooks or records show that side of him. As reported, I think the mathematical half of the case is the stronger one, because another historian can test it against the same images. The sociable Newton will stand or fall on the citations inside the book.

Feingold said coming to the material fresh helped. "We were not hamstrung by certain preconceptions about what Newton should be doing, philosophical or otherwise," he said ^[12]. The pair are longtime Newton scholars, and their first joint book, Newton and the Origin of Civilization, appeared in 2012 ^[14]. Buchwald also credited the work that came before theirs. "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," he said ^[11].