“But why?”

“Let’s not ask why,” Galileo requested.

For Piccolomini this brought back memories of his boyhood lessons, and of poor Cosimo, long since dead. “And how then did you deal with it, maestro?”

Galileo insisted on demonstrating the truth of his old finding with a model before proceeding any further. He made use of the glass urinal in his room for the model’s bottom mold, and the cathedral artisans made a wooden inner mold to fit it, filling the wood with shot to make it heavy. Then it was placed in the urinal such that, as Piccolomini said, “you couldn’t fit a piaster between them.” After that Galileo had a flask of quicksilver brought in, and he poured it into the gap between the glass and wood; and though the weight of the quicksilver was less than a twentieth that of the shot-filled wooden form, the form rose up a finger or two higher than it had been. Almost all the quicksilver pooled at the bottom of the urinal.

“Even Mercury’s silver urine gives wings to things,” Galileo joked, head cocked to the side.

Piccolomini laughed obligingly. “A very clear demonstration,” he said happily. “But then, this being the case, strange though it seems, what should we do about casting our bell?”

Galileo shoved down on the wooden mold with his hand. “The inner mold, heavy or not, has to be fixed in place like the outer one. To prevent it rising, you will need to bolt it to a pavement below. Use the heaviest beams and bolts, and all should be well.”

So they did as he had recommended, and the bell was cast successfully. Regarding the bright new thing when it emerged from its massive mold, for a moment Galileo appeared content.

But that night he howled more painfully than ever.

Cartophilus got up and found him collapsed over a railing, in the stairwell of the bell tower overlooking the piazza where the famous horse race was soon to be run. He was barking into the dark space of the stairwell, then groaning in a kind of harmony as the echoes bounced up and down it. He had been weeping so hard he could barely see; the light of the ancient servant’s candle lantern seemed to hurt his eyes.

“You must not have had your glass of milk before bed,” Cartophilus said, sitting down heavily beside him. “I told you never to neglect that.”

“Shut up,” Galileo moaned piteously. “Talking of milk when they’ve thrown me in hell.”

“It could be worse,” Cartophilus pointed out.

Silence.

Then Galileo growled. It was his wounded bear growl, and the old servant, surprised to hear it, could not help but smile. Once in the Bel-losguardo years the two of them had witnessed a bearbaiting in Florence, and late in the fight the baiters had poked the bloodied bear in the back, to get it to come out of its corner and fight the dogs, and it had briefly glanced up over its shoulder at its tormentors and growled—a low sound, bitter and resigned, that stood the hair upright on the necks of everyone who heard it. On the way home Galileo had imitated the sound over and over. “That’s me,” he told Cartophilus when he got it to his satisfaction. “That’s my growl. Because they’ve got me cornered, and they’ll make me fight.”

Now, these many years later, the same sound vibrated out of his hulk and filled the stairwell. “Errrrrrrrrrrrrrrr …” By his glance at Cartophilus, the old servant knew Galileo was reminding him of that moment in Florence, his recognition of the ursine fate awaiting him.

“Yes yes,” Cartophilus murmured, as he tugged the old man back toward his room. “But it could be worse, that’s all I’m saying. You need to remember that. You need to pick yourself up somehow and carry on.”

Galileo clutched him by the arm. “Send me back,” he demanded hoarsely. “One more time. Send me to Hera.”

“All right,” Cartophilus said after a pause. “If you want. Let’s go.” And later that night the old man fell into one of his syncopes.

The more the Soul strives after the intelligible, the more it forgets … In this sense, therefore, we may say that the good soul is forgetful.

—PLOTINUS, The Enneads

HERA APPROACHED HIM wearing white. They were back at her Ionian temple, high above the sulphurous landscape of her volcano moon. Galileo’s heart leaped to see her. He extended his arms, but she stopped short of them, looking down at him with her amused expression. His heart knocked inside him like a child trying to escape.

“So,” she said, “you escaped your fiery alternative.”

“I did,” he said. “That time, anyway.” A flash of anger shocked him: “I never deserved it!”

“No.”

“And you—you’re still here!”

“I’m still here. Of course.”

“But what about that Galileo who burned? You sent me back to the fire, and it had already happened to me, even though when you sent me back I was younger than that.”

She shook her head. “You still don’t understand. All the potentialities are entangled. They are all vibrating in and out of each other, all the time. In the e time they resonate. We saw that for a time, when we were in Jupiter. I did anyway.”

“I did too.”

“So there you have it.”

Galileo threw up his hands. “So what did Ganymede think he was doing, then? Why did he want me to burn?”

She led him to a bench and they sat on it side by side, overlooking the slaggy downslope of the yellow mountain. She took his hand. “Ganymede has an idea about time that he insists on even now. Whether he comes from our future or not is unclear. I took your suggestion and had a look at him with the mnemonic, and I think it may be true. I don’t recognize much that I saw from his childhood. The Ganymede period, however, was clear. It was as I suspected. He made an incursion into the Ganymedean ocean with a small group of supporters, and there he learned of the Jovian mind and the minds beyond. How he learned so much more than the Europans I don’t know, and maybe that’s another confirmation that he came back to us from a future time. But at that point he began making analepses using one of the entanglers, focusing on the beginning of science. He sees that start and the encounter with the alien consciousness as parts of a single whole, a situation that he has been trying for centuries to alter in both our times. These he believes are crux points in the organism—sensitivities where small changes can have big effects. I think his working theory is that the more scientific culture becomes, the better chance it will have to survive first contact with an alien consciousness. Anyway, what is certain is that he has made more analepses than anyone else. His brain is simply stuffed with these events, which are often traumas to him. He must think they help. He must think that since each one collapses the wave function of potentialities, it changes the sum over histories and therefore the main flow of events. So he made scores of bilocations—hundreds of them. It’s like he’s kicking the bank of the stream over and over again, trying to carve a new channel.”

“And has he succeeded?” Galileo asked. “And—are the years that follow really worse if I am spared? Have billions really died because of it?”

“Not necessarily.” She took his hand in hers. “There are more than two alternatives here, as everywhere. Every analepsis creates a new one, so there is a sense in which we can’t be sure what Ganymede has done, because we can’t see it. There are times where you are martyred. But we know there is also a stream of potentialities in which you succeeded in convincing the pope to your point of view, and the Church then took science under its wing and blessed it, even made it a tool of the Church.”

“There is such a time?” Galileo asked, amazed.

“Yes.”

“Why didn’t you tell me?”

“I didn’t want you to know. I thought if you knew, you would try for that outcome no matter what.”