“Nothing that cannot heal, God willing. I have been staring into the sun too much.”

“Oh.” Daniel was semi-dumbstruck by Puritan guilt for having left Isaac alone for so long. It was fortunate he hadn’t killed himself.

“I can still work in a dark room, with the spectra that are cast through the prism by the Sun. But the spectra of Venus are too faint.”

“Of Venus?!”

“I have made observations concerning the nature of Light that contradict the theories of Descartes, Boyle, and Huygens,” Isaac said. “I have divided the white light of the Sun into colors, and then recombined these rays to make white light again. I have done the experiment many times, changing the apparatus to rule out possible sources of error. But there is one I have yet to eliminate: the Sun is not a point source of light. Its face subtends a considerable arc in the heavens. Those who will seek to find fault with my work, and to attack me, will claim that this-the fact that the light entering my prism, from different parts of the Sun’s disk, strikes it from slightly different angles-renders my conclusions suspect, and therefore worthless. In order to defeat these objections I must repeat the experiments using light, not from the Sun, but from Venus-an almost infinitely narrow point of light. But the light from Venus is so faint that my burned eyes cannot see it. I need you to make the observations with your good eyes, Daniel. We begin tonight. Perhaps you’d care to take a nap?”

The house was divided in half, north/south: the northern part, which had windows but no sunlight, was the domain of Newton’s mother-a parlor on the ground floor and a bedchamber above it, both furnished in the few-but-enormous style then mandatory. The southern half-with just a few tiny apertures to admit the plentiful sunlight-was Isaac’s: on the ground floor, a kitchen with a vast walk-in fireplace, suitable for alchemical work, and above it a bedchamber.

Isaac persuaded Daniel to lie down in, or at least on, his mother’s bed for a bit of a nap-then made the mistake of mentioning that it was the same bed in which Isaac had been born, several weeks premature, twenty-four years earlier. So after half an hour of lying in that bed, as rigid as a tetanus victim, looking out between his feet at the first thing Isaac had ever laid eyes on (the window and the orchard), Daniel got up and went outside again. Isaac was still sitting on the bench with a book in his lap, but his gold spectacles were aimed at the horizon. “Defeated them soundly, I should say.”

“I beg your pardon?”

“When it started it was close to shore-but it has steadily moved away.”

“What on earth can you you talking about, Isaac?”

“The naval battle-we are fighting the Dutch in the Narrow Seas. Can you not hear the sound of the cannons?”

“I’ve been lying quietly in bed and heard nothing.”

“Out here, it is very distinct.” Isaac reached out and caught a fluttering petal. “The winds favor our Navy. The Dutch chose the wrong time to attack.”

A fit of dizziness came over Daniel just then. Partly it was the thought that James, Duke of York, who a couple of weeks ago had been standing arm’s length from Daniel discoursing of syphilis, at this moment stood on the deck of a flagship, firing on, and taking fire from, the Dutch fleet; and the booms rolled across the sea and were gathered in by the great auricle of the Wash, the Boston and the Lynn Deeps, the Long Sand and the Brancaster Roads perhaps serving as the greased convolutions of an ear, and propagated up the channel of the Welland, fanned out along its tributary rivers and rills into the swales and hills of Lincolnshire and into the ears of Isaac. It was partly that, and partly the vision that filled his eyes: thousands of white petals were coming off the apple trees and following the same diagonal path to the ground, their descent skewed by a breeze that was blowing out toward the sea.

“Do you remember when Cromwell died, and Satan’s Wind came along to carry his soul to Hell?” Isaac asked.

“Yes. I was marching in his funeral procession, watching old Puritans getting blown flat.”

“I was in the schoolyard. We happened to be having a broad-jumping competition. I won the prize, even though I was small and frail. In fact, perhaps I won because I was so-I knew that I should have to use my brains. I situated myself so that Satan’s Wind was at my back, and then timed my leap so that I left the ground during an especially powerful gust. The wind carried my little body through space like one of these petals. For a moment I was gripped by an emotion-part thrill and part terror-as I imagined that the wind might carry me away-that my feet might never touch the earth again-that I would continue to skim along, just above the ground, until I had circumnavigated the globe. Of course I was just a boy. I didn’t know that projectiles rise and fall in parabolic curves. Be those curves ever so flat, they always tend to earth again. But suppose a cannonball, or a boy caught up in a supernatural wind, flew so fast that the centrifugal force (as Huygens has named it) of his motion around the earth just counteracted his tendency to fall?”

“Er-depends on what you assume about the nature of falling,” Daniel said. “Why do we fall? In what direction?”

“We fall towards the center of the earth. The same center on which the centrifugal force pivots-like a rock whirled on the end of a string.”

“I suppose that if, somehow, you could get the forces to balance just so, you’d keep going round and round, and never fall or fly away. But it seems terrifically improbable-God would have to set it up just so-as He set the planets in their orbits.”

“If you make certain assumptions about the force of gravity, and how the weight of an object diminishes as it gets farther away, it’s not improbable at all,” Isaac said. “It just happens. You would keep going round and round forever.”

“In a circle?”

“An ellipse.”

“An ellipse…” and here the bomb finally went off in his head, and Daniel had to sit down on the ground, the moisture of last year’s fallen apples soaking through his breeches. “Like a planet.”

“Just so-if only we could jump fast enough, or had a strong enough wind at our backs, we could all be planets.”

It was so pure and obviously Right that it did not occur to Daniel to question Isaac about the details for several hours, as the Sun was going down, and they were preparing for Venus to wheel round into the southern sky. “I have developed a method of fluxions that renders it all perfectly obvious,” Isaac said.

Daniel’s first thought had been I have to tell Wilkins because Wilkins, who had written a novel in which men flew to the moon, would be delighted with Isaac’s phrase: We could all be planets. But that put him in mind of Hooke, and the experiment at the deep well. Some premonition told him that he had best keep Newton and Hooke in separate cells for now.

Isaac’s bedroom might have been designed specifically for doing prism experiments, because one wanted an opening just big enough to admit a ray of light in which to center the prism, but otherwise the room needed to be dark so that the spectrum could be clearly viewed where it struck the wall. The only drawback for Daniel was stumbling over debris. This was the room where Isaac had lived in the years before going to Cambridge. Daniel inferred that they had been lonely years. The floor was cluttered with stuff Isaac had made but been too busy to throw away, and the white plaster walls were covered with graffiti he had sketched with charcoal or scratched with nails: designs for windmills, depictions of birds, geometrickal proofs. Daniel shuffled through the darkness, never lifting a foot off the floor lest it come down on an old piece of doll-furniture or jagged remains of a lens-grinding experiment, the delicate works of a water-clock or the papery skull of a small animal, or a foamy crucible crowned with frozen drips of metal.