Whyhe was doing so, Daniel had no idea. It was just that by getting up and leaving so mysteriously, Isaac begged to be followed. Not that he was doing a good job of being sneaky. Isaac was accustomed to being so much brighter than everyone else that he really had no idea of what others were or weren’t capable of. So when he got it into his head to be tricky, he came up with tricks that would not deceive a dog. It was hard not to be insulted-but being around Isaac was never for the thin-skinned.

They continued to live together at Trinity, though now they shared a cottage without the Great Gate. They performed experiments with lenses and prisms, and Isaac went to a hall twice a week and lectured to an empty room on mathematical topics so advanced that no one else could understand them. So in that sense nothing was different. But lately Isaac had obviously lost interest in optics (probably because he knew everything about the subject now) and become mysterious. Then three days ago he had announced, with studied nonchalance, that he was going to nip down to London for a few days. When Daniel had announced that he was planning to do the same-to pay a visit to poor Oldenburg, and attend a Royal Society meeting-Isaac had done a poor job of hiding his annoyance. But he had at least tried to hide it, which was touching.

Then, halfway to London, Daniel (as a sort of experiment) had professed to be shocked that Isaac intended to lodge in an inn. Daniel would not hear of it-not when Raleigh had put so many Waterhouse assets into constructing a large new house on Holborn. At this point Isaac’s eyes had bulged even more than usual and he had adopted his suffering-martyr look, and relented only when Daniel mentioned that Raleigh’s house was so large, and had so many empty rooms, that Daniel wasn’t sure if they would ever see each other.

Daniel’s hypothesis, based on these observations, was that Isaac was committing Sins Against Nature with someone, but then certain clues (such as that Isaac never received any mail) argued against this.

As he stood there in front of the coffee-house, a gentleman*rode out of St. Martin’s Lane, reined in his horse, stood up in the stirrups, and surveyed the ongoing low-intensity riot that was Charing Cross, looking anxious until he caught sight of whatever he was looking for. Then he relaxed, sat down, and rode slowly in the general direction of-Isaac Newton. Daniel sat down in that wee garden in front of Mrs. Green’s, and ordered coffee and a newspaper.

King Carlos II of Spain was both feeble and sick, and not expected to live out the year. Comenius was dying, too. Anne Hyde, the Duke of York’s wife, was very ill with what everyone assumed to be syphilis. John Locke was writing a constitution for Carolina, Stenka Razin’s Cossack rebellion was being crushed in the Ukraine, the Grand Turk was taking Crete away from Venice with his left hand and declaring war on Poland with his right. In London, the fall of pepper prices was sending many City merchants into bankruptcy-while a short distance across the Narrow Seas, the V.O.C.-the Dutch East India Company-was paying out a dividend of 40 percent.

But the news was of the doings of the CABAL*and the courtiers. John Churchill was one of the few courtiers who actually did things like go to Barbary and go mano a mano with heathen corsairs, and so there was plenty concerning him. He and most of the rest of the English Navy were blockading Algiers, trying to do something, at long last, about the Barbary Pirates.

The gentleman on horseback had a courtier look about him, though unfashionably battered and frayed. He had nearly ridden Daniel down a few minutes previously when Daniel had emerged from Raleigh’s house and foolishly planted himself in the middle of the road trying to catch sight of Isaac. He had the general look of a poor baron from some slaty place in the high latitudes who wanted to make a name for himself in London but lacked the means. He was dressed practically enough in actual boots, rather than the witty allusions to boots worn by young men about town. He wore a dark cassock-a riding garment loosely modeled after a priest’s tent-like garment-with numerous silver buttons. He had an expensive saddle on a mediocre horse. The horse thus looked something like a fishwife dressed up in a colonel’s uniform. If Isaac was looking for a mistress (or a master or whatever the sodomitical equivalent of a mistress was), he could’ve done worse and he could’ve done better.

Daniel had brought a Valuable Object with him-not because he’d expected to use it, but out of fear that one of Raleigh’s servants would wreck or steal it. It was in a wooden case buckled shut, which he had set on the table. He undid the buckles, raised the lid, and peeled back red velvet to divulge a tubular device about a foot long, fat enough that you could insert a fist, closed at one end. It was mounted on a wooden sphere the size of a large apple, and the sphere was held in a sort of clamp that gave it freedom to rotate around all axes-i.e., you could set it down on a tabletop and then point the open end of the tube in any direction, which was how Daniel used it. Bored through the tube’s wall near the open end was a finger-sized hole, and mounted below this, in the center of the tube, was a small mirror, angled backwards at a concave dish of silvered glass that sealed the butt of the tube. The design was Isaac’s, certain refinements and much of the construction were Daniel’s. Putting an eye to the little hole, he saw a colored blur. Adjusting a thumbscrew at the mirror end, and thereby collapsing the tube together a bit, he resolved the blur into a chunk of ornamented window-frame with a lace curtain being sucked out of it, down at the other end of Charing Cross. Daniel was startled to realize that he was looking all the way across the Great Court that lay before Whitehall Palace, and peering in through someone’s windows-unless he was mistaken, these were the apartments of Lady Castlemaine, the King of England’s favorite mistress.

Nudging it round to a slightly different bearing, he saw the end of the Banqueting House, where King Charles I had been beheaded, back when Daniel had been small-Divine Right of Kings demolished, the Commonwealth founded, Free Enterprise introduced, Drake happy for once, and Daniel sitting on his shoulders, watching the King’s head rock. In those days, all of Whitehall’s windows that faced the outside had been bricked up to keep musket-balls out, and many superstitious fopperies, e.g., paintings and sculptures, had been crated up and sold to Dutchmen. But now the windows were windows again, and the artworks had been bought back, and there wasn’t a decapitated King in sight.

So it was not a good time to reminisce about Drake. Daniel swiveled the Reflecting Telescope around until the ragged plume in the horseman’s hat showed up as a bobbing white blur, like the tail of a hustling rabbit. Once he’d focused on that, a couple of tiny adjustments brought Isaac’s waterfall of argent hair into view-just in time, for he was ascending a few steps into a building across from the Haymarket, along the convergence of traffic that eventually became Pall Mall. Daniel played the telescope around the front of the building, expecting it to be a coffee-house or pub or inn where Isaac would await his gentleman friend. But he was completely wrong. To begin with, this place was apparently nothing more than a town-house. And yet well-dressed men came and went occasionally, and when they emerged, they (or their servants) were carrying packages. Daniel reckoned it must be some sort of shop too discreet to announce itself-hardly unusual in this part of London, but not Isaac’s sort of place.