What type of plague closed Cambridge in 1665, sending Newton back to Woolsthorpe?

The plague that closed Cambridge in 1665 was bubonic plague. It was part of the Great Plague outbreak that spread through England in 1665–1666 and prompted the University of Cambridge to send students away.

Newton returned to Woolsthorpe in Lincolnshire, where he spent much of the plague years working independently. During this period, he developed important ideas about infinite series, methods related to calculus, optics, and the relationship between gravity and planetary motion. The later popular phrase “miracle years” refers to this unusually productive period rather than to a formal period of quarantine in the modern sense.

Bubonic plague was caused by the bacterium Yersinia pestis and was commonly associated with swollen lymph nodes called buboes. The outbreak is sometimes called the Great Plague of London, but its effects extended beyond London. “Black Death” is also a common mix-up: that usually refers to the fourteenth-century pandemic, while Newton lived through the later seventeenth-century outbreak.