Daniel recalled driving past shredded corpses at Tyburn. “You mean that weighers are connected with coiners.”

“As spinners are with weavers, Daniel.”

Daniel was silent for a moment, rehearsing every memory he had of Mr. Threader.

“That is why I was so shocked-shocked half to death, if you must know-to see you traveling in the company of one such!” Isaac said, actually shaking a bit with emotion.

Daniel was so used to Isaac mysteriously knowing things, that he was not as surprised by this very odd revelation as he ought to have been, and did not pay any particular mind to it. “For that,” he remarked, “there is an explanation that you would find miserably boring if you knew it.”

“I have made it my business to know it, and I accept that there was nothing untoward in your temporary association with that man,” Isaac returned. “If I were inclined to be suspicious, like Flamsteed, I should interpret your continued association with him in the worst possible light! As it is, I see plainly enough that you were ignorant of his true nature, and beguiled by his charm, and I trust you to heed my warning.”

Daniel was now very close to laughing out loud. He could not choose which was funnier: the phant’sy that Isaac Newton was not suspicious-minded, or that Mr. Threader possessed charm. Better change the subject! “But my question is not answered yet. Why did he bite the coin, if he had already weighed it?”

“There is a way to fool the weighing-test,” Isaac said.

“Impossible! Nothing is heavier than gold!”

“I have discovered the existence of gold of greater than twenty-four-carat weight.”

“That is an absurdity,” Daniel said, after a moment’s pause to consider it.

“Your mind, being a logical organ, rejects it,” Isaac said, “because, by definition, pure gold weighs twenty-four carats. Pure gold cannot become purer, hence, cannot be heavier. Of course, I am aware of this. But I say to you that I have with my own hands weighed gold that was heavier than gold that I knew to be pure.”

From any other man on earth-Natural Philosophers included-this would amount to saying, “I was sloppy in the laboratory and got it wrong.” From Sir Isaac Newton, it was truth of Euclidean certainty.

“I am put in mind of the discovery of phosphorus,” Daniel remarked, after considering it for a few moments. “A new element of nature, with properties never before seen. Perhaps there exist other elements of which we are unaware, having properties hitherto unknown. Perhaps there is such an element, similar in many respects to gold, but having a higher specific gravity, and perhaps the gold you spoke of was alloyed with it to make a metal, indistinguishable from gold in its gross properties, but slightly more dense.”

“I give you credit for ingenuity,” Isaac said, slightly amused, “but there is a simpler explanation. Yes, the gold I speak of is alloyed with something: a fluidic essence that fills the interstices among its atoms and gives the metal greater weight. But I believe that this essence is nothing less than-”

“The Philosophick Mercury!” Daniel exclaimed. The words came out of his mouth in a spirit of genuine excitement; bounced off the hard walls of dark wood; and, when they entered his ears, made him cringe at his own idiocy. “You think it is the Philosophick Mercury,” he corrected himself.

“The Subtile Spirit,” Isaac said, not excited, but solemn as Rhadamanthus. “And the goal of Alchemists for thousands of years, ever since the Art was taken into the Orient, and removed from human ken, by its past master, King Solomon.”

“You have been searching for traces of the Philosophick Mercury since we were boys,” Daniel reminded him. “As recently as twenty years ago, your efforts to find even the smallest trace of it had met with abject failure. What has changed?”

“I took your advice, Daniel. I accepted the charge of the Mint from my lord Ravenscar. I initiated the Great Recoinage, which brought vast tonnage of gold plate and bullion out from where it had been hoarded.”

“And you adjusted the ratio in valuation of silver to gold, so that the latter was over-valued,” Daniel said, “which as everyone knows, has practically driven all silver off the island, and attracted gold from every corner of the globe where commerce has spread its tendrils.”

Isaac declined comment.

“Prior to your-” here Daniel was about to say something like terrifying spasm of dementia but corrected himself: “change of career, twenty years ago, you were only able to work with such modest samples of gold as you could buy from local sources. Your appointment to the Mint-combined with the policies you have adopted there-have made the Tower of London the bottle-neck through which all the world’s gold flows, and put you in a position to dip your finger into that flow at will, sampling and testing the gold of many different lands-am I getting it right?”

Isaac nodded, and it seemed he looked almost mischievous, in a naughty-old-man sort of way. “The practice of all Alchemists since the time of Hermes Trismegistus has been to presume that the Gold of Solomon had been forever lost, and to attempt to re-discover his lost Art through patient trials and arcane study. This was the course that defeated me, before what you coyly describe as my change of career. But during my recuperation, as I went to inspect the Mint, and conversed with my predecessors there, I came to realize that the ancient presumption of the Esoteric Brotherhood was no longer true. If Solomon went away into the remotest isles of the Orient, why, Commerce has now gone that far, or farther, and in particular the Spaniards and the Portuguese have left no stone unturned, the world over, in their assiduous search for gold and silver. No matter how far Solomon may have journeyed, he would have left behind traces of his passage, in the form of Solomonic Gold, which is to say, gold made through an Alchemical process, bearing traces of the Philosophick Mercury. In the millennia since his kingdom vanished from the earth, this gold might have passed from one ignorant set of hands to another a thousand times. It might have been taken across wastes by caravans, forged into pagan funeral-masks, plundered from fallen citadels, buried in secret hoards, dug up by thieves, seized by pirates, made into jewels, and coined into specie of diverse realms. But through all of these evolutions it would preserve the traces of the Philosophick Mercury that would provide an infallible proof of its origins. To find it, I need not pore over ancient manuscripts for fragments of Alchemical lore, and I need not venture into far reaches to search for ancient gold with my own hands. I need only position myself like a spider at the center of the global web of commerce, and then so arrange matters that all the world’s gold would flow inwards toward me, as every point of matter in the solar system naturally falls inwards toward the Sun. If I then remained vigilant, and sampled all the gold that came into the Mint to be made into guineas, in time I should be nearly certain of finding some traces of the Solomonic Gold.”

“And now you would appear to have found it,” said Daniel, unwilling to weigh in, yet, on Isaac’s side. “How recently has this occurred?”

“For the first several years there was nothing. Not a trace. I despaired of finding it ever,” Isaac admitted. “Then, during the respite in the War, round 1701, I found a bit of gold heavier than twenty-four carat. I cannot summon words, here and now, to convey my emotions then! It was just a flake of gold leaf, found in a coiner’s shop after it was raided, on my orders, by the King’s Messengers. The coiner himself had been slain during the raid-most frustrating! Several years later, I found a counterfeit guinea that was heavier than it ought to be. In time, I hunted down the coiner who had made it, and interrogated him as to where he had obtained his bullion. He had gotten most of it from conventional sources. But he said that he had recently purchased, through a middleman, a quantity of gold in the form of sheet metal, hand-hammered, about an eighth of an inch thick. Six months later I talked to another coiner who recollected having seen a larger piece of such gold. He said it had been marked on one side with a linear pattern of scrapes, and stained on the other face with tar.”