"Any sentient man can perceive that," Leibniz returned. "Almost all will be so blinded by its brilliance that they will be unable to perceive its flaws. There are only a few of us who can do that."
"It is very easy to carp."
"Actually it is rather difficult, in that it leads to discussions such as this one."
"Unless you can propose an alternative theory that mends these supposed flaws, I believe you should temper your criticisms of the Principia."
"I am still developing my theory, Monsieur Fatio, and it may be a long time before it is capable of making testable predictions."
"What conceivable theory could explain the discernibility of those two planets, without making reference to their positions in absolute space?"
THIS LED TO AN INTERLUDE in the snow outside. Doctor Leibniz packed two handfuls of snow together between his hands, watched warily by Fatio. "Don't worry, Monsieur Fatio, I'm not going to throw it at you. If you would be so helpful as to make two more, about the size of melons, as like to each other as possible."
Fatio was not quick to warm to such a task, but eventually he squatted down and began to roll a pair of balls, stopping every couple of paces to pound away the rough edges.
"They are as close to indiscernible as I can make them under these conditions—which is to say, in twilight with frozen hands," shouted Fatio towards Leibniz, who was a stone's throw off, wrestling with a snowball that weighed more than he did. When no response came back, he muttered, "I shall go in and warm my hands if that is acceptable."
But by the time Nicolas Fatio de Duillier had got back to Leibniz's office, his hands were warm enough to do a few things. He took another look at the papers stuck into the Chinese book. The letter from Eliza was inordinately long, and appeared to consist entirely of gaseous chatter about what everyone was wearing. Yet on top of it was the other document, addressed to the Doctor but written in the Doctor's hand. A mystery. Perhaps the book was a clue? It was called I Ching. Fatio had seen it once before, in the library of Gresham's College, where Daniel Waterhouse had fallen asleep over it. The sheaf of papers had been used to mark a particular chapter entitled: 54. Kuei Mei: The Marrying Maiden. The chapter itself was a bucket of claptrap and mystickal gibberish.
He put it back where he'd found it, and went over to the shed's single tiny window. Leibniz now had his back pressed against an immense snowball and was trying to topple it over by thrusting with both legs. Fatio strolled once around the room, pausing to riffle through any prominent stacks of papers that presented themselves to his big pale eyes. Of which there were severaclass="underline" letters from Huygens, from Arnauld, from the Bernoullis, the late Spinoza, Daniel Waterhouse, and everyone else in Christendom who had a flicker of sense. But one of the larger stacks consisted of letters from Eliza. Fatio reached into the middle, grabbed half a dozen leaves between his thumb and index finger, and snapped them out. He folded them and stuffed them into his breast pocket. Then he ventured back outside.
"Are your hands warm, Monsieur Fatio?"
"Exceeding warm, Doctor Leibniz."
The Doctor had arranged the three snowballs—one giant one and the two small indiscernibles—on the field between the stable, the Schloß, and the nearby Arsenal. The triangle defined by these balls was nothing special, being neither equilateral nor isosceles.
"Isn't this how Sir Francis Bacon died?"
"Descartes, too—froze to death in Sweden," the Doctor returned cheerfully, "and if Leibniz and Fatio can go down in the annals next to Bacon and Descartes our lives will have been well concluded. Now, if you would be so good as to go to that one and tell me of your perceptions." The Doctor pointed to a small snowball a few paces in front of Fatio.
"I see the field, the Schloß, Arsenal, and Library-to-be. I see you, Doctor, standing by a great snowball, and over there to the right, not so far away, a lesser one."
"Now pray do the same from the other snowball that you made."
A few moments later Fatio was able to report: "The same."
"Exactly the same?"
"Well, of course there are slight differences. Now, Doctor, you and the large snowball are to my right, and closer than before, and the small snowball is to my left."
Leibniz now deserted his post and began stomping towards Fatio. "Newton would have it that this field possesses a reality of its own, which governs the balls, and makes them discernible. But I say the field is not necessary! Forget about it, and consider only the balls' perceptions."
"Perceptions?"
"You said yourself that when you stood there you perceived a large snowball on the left, far away, and a small one on the right. Here you perceive a large one on the right, near at hand, and a small one on the left. So even though the balls might be indiscernible, and hence identical, in terms of their external properties such as size, shape, and weight, when we consider their internal properties—such as their perceptions of one another—we see that they are different. So they are discernible! And what is more, they may be discerned without reference to some sort of fixed, absolute space."
By now they had, without discussion, begun trudging back towards the Schloß, which looked deceptively warm and inviting as twilight deepened.
"You seem to be granting every object in the Universe the power to perceive, and to record its perceptions," Fatio ventured.
"If you are going to venture down this road of subdividing objects into smaller and smaller bits, you must somewhere stop, and stick your neck out by saying, ‘This is the fundamental unit of reality, and thus are its properties, on which all other phænomena are built,' " said the Doctor. "Some think it makes sense that these are like billiard balls, which interact by colliding."
"I was just about to say," said Fatio, "what could be simpler than that? A hard wee bit of indivisible matter. That is the most reasonable hypothesis of what an atom is."
"I disagree! Matter is complicated stuff. Collisions between pieces of matter are more complicated yet. Consider: If these atoms are infinitely small, why, then, is it not true that the likelihood of one atom colliding with another is essentially zero?"
"You have a point," said Fatio, "but I hardly think it is somehow simpler to endow these atoms, instead, with the ability to perceive and to think."
"Perception and thought are properties of souls. It is no worse to posit that the fundamental building-block of the Universe is souls than to say it is wee bits of hard stuff, moving about in an empty space that is pervaded by mystickal Fields."
"Somehow a planet's perception of the sun and all the other planets, then, causes it to behave exactly as if it were in such a ‘mystickal Field,' to an uncanny degree of precision."
"I know it sounds difficult, Monsieur Fatio, but 'twill work out better in the long run."
"Physics, then, becomes a sort of vast record-keeping exercise. Every object in the Universe is distinguished from every other object by the uniqueness of its perceptions of all the other objects."
"If you think on it long enough you will see it is the only way to distinguish them."
"Why, it is as if every atom or particle—"
"I call them monads."
"Monad, then, is a sort of Knowledge Engine unto itself, a Bücherrad-rad-rad-rad…"
Leibniz summoned a weak smile.
"Its gears grind away like the ones in your Arithmetickal Engine, and it decides what to do of its own accord. You knew Spinoza, did you not?"
Leibniz held up a warning hand. "Yes. But pray do not put me in with him."
"If I may just return to the topic that got us started, Doctor, it seems to me that your theory allows for a possibility you scoffed at—namely, that two lumps of gold might be different from each other."