PART ONE

COUNTING AND THINKING

Natural Philosophy consists in discovering the frame and operations of Nature, and reducing them, as far as may be, to general Rules or Laws,—establishing these rules by observations and experiments, and thence deducing the cause and effects of things.

—ISAAC NEWTON

CHAPTER ONE

“The System of the World”

WOOLSTHORPE, LINCOLNSHIRE, MIDSUMMER, 1665

He had walked for three days to escape a farmer’s life just four years before. There’d been no hint he’d ever return. Yet, here he was again, about to open the gate. Little had changed: the main house, stone-built, comfortable; the barn behind; and, just across the track from the front door, the little patch of garden with its stand of apple trees, warming in the early-summer sun. He’d been nineteen when he left, a country boy, awkward and unsociable, much given to scribbling in his notebook. He was twenty-three now and had a place in the world: a scholar of Trinity College, Cambridge, with rooms and a stipend and his own place at table. But now, smack in the middle of term, he was coming up the lane, crossing to the door, and stepping over the threshold, into the house.

Isaac Newton had come home.

Or rather, he had been chased back to Woolsthorpe’s quiet corner of the Lincolnshire countryside. Cambridge had been emptying since late spring, as each of its seven thousand or so residents who had anywhere to go desperately fled the approaching danger. That threat had been carried in its turn by those coming up the roads from London, on the run from the terror that had already reached the capital.

No one knows precisely how the plague reached London in the early months of 1665. Attentive observers had been nervous throughout 1664. The diarist and navy bureaucrat Samuel Pepys kept his eyes on Amsterdam, where a full-blown epidemic had begun in the previous fall. Pepys first took note of the danger in October, and then in November recorded in his diary that ships coming from infected ports now faced quarantine along the Thames. But some still arrived, smugglers carrying cloth, or, after the new year, with the start of the second Anglo-Dutch War, vessels bringing prisoners home. There were always rats on board, and rats carry fleas. Fleas host the Yersinia pestisbacterium.

Y. pestiscauses the plague.

Winter came, the slowest season for infection. For a time, it appeared that England might escape the scourge suffered on the other side of the North Sea. A few cases were reported. The bill of mortality for the crowded parish of St. Giles in the Fields records one plague death on Christmas Eve, 1664—a “Goodwoman Phillips.” When she fell ill, Phillips, her husband, and their unnamed and unnumbered children were placed in quarantine, and their home was shuttered, guarded, and bedaubed with the plea “Lord Have Mercy on Us.” But the infection apparently stopped there, and the next weeks were quiet. Plague was endemic in England, and every year saw a few come down with the disease. This appeared to be just one more case, and not the first of a new tidal wave of infection.

The winter ended, and spring began kindly. Two more plague deaths show up in London’s weekly bills of mortality in the last week of April, again in St. Giles in the Fields. The first week in May saw none…but then the numbers turned. Nine in the second week, three in the third. Fourteen for the week of May 23. Seventeen reported on the thirtieth. Forty-three on June 6—and the tally leapt from there. The official record topped a thousand on July 28, then doubled, and doubled again. By September, one thousand Londoners were dying each day. By year’s end, the official toll would approach seventy thousand, as many as one in eight of the city’s residents.

Everyone who could get out of town did. On June 21, the ubiquitous Pepys, secretary to the Admiralty, had a meeting in Whitehall, trying to unravel King Charles II’s perpetual money troubles. Achieving nothing more than usual, he set out across the city to Cripplegate, one of the ancient openings in London’s city wall.