At some point Fatio had to tear those eyes away from Eliza and begin the same sort of dance- cum-duel with Waterhouse. Again, if Fatio had been a Fellow of the Royal Society, or a Doctor at some university, Waterhouse would have had some idea what to make of him; as it was, Fatio had to conjure his credentials and bona fides out of thin air, as it were, by dropping names and scattering references to books he’d read, problems he’d solved, inflated reputations he had punctured, experiments he had performed, creatures he had seen. “I had half expected to see Mr. Enoch Root here,” he said at one point, looking about, “for a (ahem) gentleman of my acquaintance here, an amateur of (ahem) chymical studies, has shared with me a rumor-only a rumor, mind you-that a man owning Root’s description was observed, the other day, debarking from a canal-ship from Brussels.” As Fatio stretched this patch of news thinner and thinner, he flinched his huge eyes several times at Waterhouse. Certain French nobles would have winked or stroked their moustaches interestedly; Waterhouse offered up nothing but a basilisk-stare.

That was the last time Fatio had anything to say concerning Alchemy; from that point onwards it was strictly mathematics, and the new work by Newton. Eliza had heard from both Leibniz and Huygens that this Newton had written some sort of discourse that had left all of the other Natural Philosophers holding their heads between their knees, and quite dried up the ink in their quills, and so she was able to follow Fatio’s drift here. Though from time to time he would turn his attention to Eliza and revert to courtly posturing for a few moments. Fatio prosecuted all of these uphill strugglings with little apparent effort, which spoke well of his training, and of the overall balance of his humours. At the same time it made her tired just to watch him. From the moment he came in the door he controlled the conversation; everyone spent the rest of the evening reacting to Fatio. That suited Eliza’s purposes well enough; it kept Daniel Waterhouse frustrated, which was how she liked him, and gave her leisure to observe. All the same, she wondered what supplied the energy to keep a Fatio going; he was the loudest and fastest clock in the room, and must have an internal spring keyed up very tight. He had no sexual interest whatever in Eliza, and that was a relief, for she could tell that he would be relentless and probably tiresome in wooing.

Why didn’t they just eject Fatio and have a peaceful dinner? Because he had genuine merit. Confronted by a nobody so desperate to establish his reputation, Eliza’s first impulse (and Waterhouse’s, too, she inferred) was to assume he was a poseur. But he was not. Once he figured out that Eliza wasn’t Catholic he had interesting things to say concerning religion and the state of French society. Once he figured out that Waterhouse was no alchemist, he began to discourse of mathematical functions in a way that snapped the Englishman awake. And Huygens, when he finally woke up and came downstairs, made it obvious by his treatment of Fatio that he rated him as an equal-or as close to equal as a man like Huygens could ever have.

“A man of my tender age and meager accomplishments cannot give sufficient honor to the gentleman who once dined at this table-”

“Actually Descartes dined here many times-not just once!” Huygens put in gruffly.

“-and set out his proposal to explain physical reality with mathematics,” Fatio finished.

“You would not speak of him that way unless you were about to say something against him,” Eliza said.

“Not against him, but some of his latter-day followers. The project that Descartes started is finished. Vortices will never do! I am surprised that Leibniz still holds out any hope for them.”

Everyone sat up straighter. “Perhaps you have heard from Leibniz more recently than I have, sir,” Waterhouse said.

“You give me more credit than I deserve, Doctor Waterhouse, to suggest that Doctor Leibniz would communicate his freshest insights to me, before despatching them to the Royal Society! Please correct me.”

“It is not that Leibniz has any particular attachment to vortices, but that he cannot bring himself to believe in any sort of mysterious action at a distance.” Hearing this, Huygens raised a hand momentarily, as if seconding a motion. Fatio did not fail to notice. Waterhouse continued, “Action at a distance is a sort of occult notion-which may appeal to a certain sort of mentality-”

“But not to those of us who have adopted the Mechanical Philosophy that Monsieur Descartes propounded at this very table!”

“In that very chair, sir!” said Huygens, pointing at Fatio with a drumstick.

“I have my own Theory of Gravitation that should account for the inverse square relation,” Fatio said. “As a stone dropped into water makes spreading ripples, so a planet makes concentric disturbances in the c?lestial ?ther, which press upon its satellites…”

“Write it down,” Waterhouse said, “and send it to me, and we will print it alongside Leibniz’s account, and may the better one prevail.”

“Your offer is gratefully accepted!” Fatio said, and glanced at Huygens to make sure he had a witness. “But I fear we are boring Mademoiselle Eliza.”

“Not at all, Monsieur, any conversation that bears on the Doctor is of interest to me.”

“Is there any topic that does not relate to Leibniz in some way?”

“Alchemy,” Waterhouse suggested darkly.

Fatio, whose chief object at the moment was to draw Eliza into the conversation, ignored this. “I can’t but wonder whether we may discern the Doctor’s hand in the formation of the League of Augsburg.”

“I would guess not,” Eliza said. “It has long been Leibniz’s dream to re-unite the Catholic and Lutheran churches, and prevent another Thirty Years’ War. But the League looks to me like a preparation for war. It is not the conception of the Doctor, but of the Prince of Orange.”

“The Protestant Defender,” Fatio said. Eliza was accustomed to hearing that phrase drenched in French sarcasm, but Fatio uttered it carefully, like a Natural Philosopher weighing an unproven hypothesis. “Our neighbors in Savoy could have used some defending when de Catinat came through with his dragoons. Yes, in this matter I must disagree with the Doctor, as well-meaning as he is… we do need a Defender, and William of Orange will make a good one, provided he stays out of the clutches of the French.” Fatio was staring at Eliza while he said this.

Huygens chuckled. “That should not be difficult, since he never leaves Dutch soil.”

“But the coast is long, and mostly empty, and the French could put a force ashore anywhere they pleased.”

“French fleets do not sail up and down the Dutch coast without drawing attention,” Huygens said, still amused by the idea.

Continuing to watch Eliza, Fatio replied, “I said nothing about a fleet. A single jacht would suffice to put a boat-load of dragoons on the beach.”

“And what would those dragoons do against the might of the Dutch army?”

“Be destroyed, if they were stupid enough to encamp on the beach and wait for that army to mobilize,” Fatio answered. “But if they happened to light on the particular stretch of beach where William goes sand-sailing, at the right time of the morning, why, they could redraw the map, and rewrite the future history, of Europe in a few minutes’ work.”

Now nothing could be heard for a minute or so except the clocks. Fatio still held Eliza fast with his vast eyes, giant blue lenses that seemed to take all the light in the room. What might they not have noticed, and what might the mind in back of them not know?

On the other hand, what tricks could the mind not conjure up, and with those eyes, whom couldn’t he draw into his snares?

“It is a clever conceit, like a chapter from a picaroon-romance,” Eliza said. Fatio’s high brow shriveled, and the eyes that had seemed so penetrating a moment ago now looked pleading. Eliza glanced toward the stairs. “Now that Fatio has provided us with entertainment, will you elevate us, Monsieur Huygens?”