“Am I not allowed to inquire after my friend in my house?”
“Of course, I just…well…never mind. I have been corresponding with those Bernoulli brothers rather a lot. Nothing important. You know I have always been fascinated with symbols and characters. The calculus has brought us new ideas for which we want new symbols. For differentiation, I like a small letter d, and for integration, a sort of elongated S. That’s how the Bernoullis have been doing it, and it suits them well. But there is another Swiss mathematician, a fellow who was once viewed as quite a promising young savant-in-the-making, by the name of Nicolas Fatio de Duillier.”
“That one who saved William of Orange from a kidnap-plot?” asked Sophie, planting the tip of Leibniz’s rapier in the tabletop and flexing it absent-mindedly.
“The same. He and the Bernoullis have been corresponding.”
“But you said, very meaningfully, that this fellow was once viewed as promising.”
“His work the last few years has been laughable. He is not right in his head, or so it would seem.”
“I thought it was Newton who had gone out of his mind.”
“I am coming to Newton. He—Fatio, that is—and the Bernoullis have, ’twould seem, been carrying on one of these slow-smoldering disputes. They send him a letter using the little d and the stretched-out S, and, tit-for-tat, he sends them one back using a little dot for differentiation and some sort of abominable “Q”-notation for integration. This is how Newton writes calculus. It is a sort of shin-kicking contest that has been going on for years. Well, a few months ago it blew up. Fatio published an article saying some very uncomplimentary things about your humble and obedient servant right here, and attributing the calculus to Newton. Then the Bernoullis cooked up a mathematicks problem and began sending it round to the Continental mathematicians to see if any of them could solve it. None of them could—”
“Not even you!?”
“Of course I could solve it, it was just a calculus problem and it had only one purpose, which was to separate the men—which is to say, those who understood the calculus—from the boys. They then sent the damned thing to Newton, who worked it out in a few hours.”
“Oh! So he is not out of his mind!”
“For all I know, Majesty, he may be entirely out of his mind—the point is, he is still without rival, when it comes to mathematicks. And now, thanks to those mischievous Bernoullis, he believes that I and all the other Continental mathematicians do conspire against him.”
“I thought you were going to talk philosophy now, not gossip.”
Leibniz inhaled to say something, stopped, and sighed it all out. Then he did it again. Then a third time. Fortuitously, the bat chose this moment to come out of hiding. Sophie was not slow to jerk the rapier free from the tabletop and return to the hunt. After a bit of random flitting here and there—for the bat seemed to phant’sy that the keening tip of the rapier was some sort of blindingly fast insect—it settled into a hunting pattern, swinging around the long perimeter of the dining room, but judiciously avoiding the corners, plotting therefore a roughly elliptical orbit. The table was planted across one end of the room and so the bat flew across it twice on each revolution. Sophie’s strategy, then, was to plant herself on the table just where she predicted the bat would over-fly it as it came in from its long patrol of the room. Missing it there, she could then rush down to the other end to take another hack at it when it rebounded from the near wall and passed over again, outward-bound.
“Your majesty’s situation vis-àvis the bat is very like that of a terrestrial astronomer when the earth’s orbit-a segment of which is here represented by the table—is intersected by that of a comet, crossing over twice, once inbound towards Sol, and once outbound.” Leibniz nodded significantly at the dazzling blaze of the candelabra, which had been set down on the floor between the table and the wall.
“Less sarcasm, more philosophy.”
“As you know, the library is being moved here—”
“I just thought, what’s the use of having a library if I must journey to Wolfenbüttel to use it? My husband never cared much for books, but now that he spends all his time in bed—”
“I do not criticize, Majesty. On the contrary, it has been good to withdraw from day-to-day management of the collection, and turn my attention to the library’s true purpose.”
“Now you really have got me confused.”
“The mind cannot work with things themselves. I see the bat over yonder, my mind is aware of it, but my mind does not manipulate the bat directly. Instead my mind is (I suppose) working with a symbolic representation of the bat that exists inside my head. I can do things to that symbol—such as imagining the bat dead—without affecting the real bat itself.”