“If you could both make the assertion, and escape the consequences of it, somehow … Yes. It will be a close run thing, but I should think it would do. There are so many potentialities, after all. How the wave function collapses at any given moment is never completely determinative of what follows. There are inertias and instabilities, and many subsequent interventions. And if there are longer-term changes that follow, I think they could be good. The histories we have now are not such that a change in the centuries subsequent to yours would be such a bad idea. It might lessen the depth of the low point, and get us here with less suffering.”

“But it might change you out of existence?”

“But here we are,” she pointed out.

“But it might still happen?”

“Maybe. But how would that make our situation any different? We might always wink out of existence, at any time.”

Galileo shuddered at the thought. “And so you will help me?”

She regarded him curiously. She seemed almost to hesitate. But then:

“Yes. I will. It will have to be done carefully, you understand. The change will have to be subtly done. And there will be people who will try to prevent any such change, you understand. Ganymede and others.”

“I understand.”

She looked up suddenly, scowled at what she saw. Galileo followed her gaze, saw the star-studded black sky and nothing more. Except then he spotted a small cluster of moving lights, like fireflies. Reinforcements from Ganymede’s people, perhaps.

Hera said, “We should return you to Ganymede.”

“What should I say to him about this?”

She smiled, it seemed at his quickness to fall into conspiracy with her. “Whatever you like,” she said. “Here on Io, you are free to speak your mind. You can tell him everything I told you, if you like.”

“Yes, of course. Thank you. But should I tell him of our plan?”

“What do you think?”

“I would rather not. If his faction believes I must be burned for history to turn out as they want it, then they might try to keep it that way, not so?”

“Exactly.”

“Then we must keep our project a secret.”

“Ha!” she said. “I’m not good at keeping secrets. I speak my mind.”

“But you said you were going to help me!”

“I am going to help you. It’s just that I may choose not to do it in secret.”

“Ah. Well, then …” Galileo was confused. “They will send me back to my time?”

“Yes.”

“And give me a preparation to make me forget what happened here, you said?”

“Yes.”

“But you can give me something to counteract their preparation?”

Her eyebrows bunched together as she thought it over. She glanced at him sidelong. “Yes,” she said, “I can. For every amnestic there are anamnestics. Although I am not so sure you will like remembering this. I can try to modulate your short-term memory, so that you remember just the outlines of it, and the feeling. But as I don’t know which amnestic they will be using, it will be tricky. I can try to counteract the whole class of drug I think they will use.” She spoke quietly into the back of her hand. “My people will give me what I think you will need. You must expect some confusion to result, whether it works or not.”

“Just so I don’t forget!”

“No. What I give you, you will take now, in advance of their application. Then hold your breath right before they send you back. He shoots a mist into your face at the last moment. If you are successful, the result should be that you remember all this fairly well. The anamnestics are quite effective, you will see. Hopefully not in a way that proves intolerable to you.”

“Good. And—will you bring me back here to you, at some point, if you can? I feel that if I am to succeed in my effort at home, I need to learn more.”

She laughed at that. “This is what you are always saying, yes?”

“So you’ll bring me back?”

“I’m not sure.”

“You’ll try?”

“Maybe. Don’t mention that to Ganymede. That should be arrheton—not to be spoken of.”

Then vessels like sealed boat hulls, standing on pillars of fire, descended around them. Hera took him by the arm and led him across the smooth yellow stone parquet of the round temple to where her people were holding the stranger and his small group. Ganymede, still there, glared at them both, his eyes burning with such curiosity that Galileo had to look away for fear his new knowledge would squirt out of him by a glance alone. Meanwhile Hera took his hand and palmed him a small pill. She leaned down to his face: “Swallow it now,” she murmured in his ear, then gave him a kiss on the cheek. He brought his hand up to his face as if to touch hers, and as she withdrew he tossed the pill in his mouth and swallowed it. It had a bitter taste, like unripe limes.

Hera had turned to the Ganymede and his newly arrived supporters, who were looking angry. She gave the pewter box to Ganymede and announced, “Here, you can have him. But let him go back where he belongs.”

“We would have long before, if it weren’t for you,” Ganymede said furiously, and then Galileo was surrounded by the stranger’s associates, and Ganymede was holding the box before him, and he held his breath tightly. But one of them noticed what he was doing and tapped him hard in the solar plexus, waited for him to suck in his breath after the involuntary exhalation, then sprayed the mist in his face.

CHAPTER EIGHT

Parry Riposte

To hope without hope, which would be wise, is impossible.

—MARCEL PROUST, Les Plaisirs et les Jours

No ONE UNDERSTOOD WHY the maestro was so anxious and melancholy after that night when Cardinal Barberini came through. It was true he had eaten and drunk too much at the banquet, and had then slept badly and eventually fallen into one of his syncopes, and come out of it too ill to attend the farewell breakfast the next morning. But none of that was particularly unusual for him, and the extremely warm letter from the cardinal should have more than reassured him about missing the send-off breakfast. Really, his anno mirabilis had lasted for almost three years now and was still going strong. He should have been happy.

But he wasn’t. His sleep was frequently broken by nightmares, and his days were irritable to him. “Something bad is going to happen,” he kept saying, looking through his telescope at Jupiter like a soothsayer. “Something monstrous wants to be born.”

One night he called Cartophilus to him. Staring at the old man over a cup of warmed milk brought to him to ward off the chill, he said suddenly, “Where is your master?”

“You are my master, maestro.”

“You know who I mean!”

“… He’s not here.”

Galileo contemplated this, frowning. Finally he said, “When I want him again, can you call him here?”

After another pause the old man nodded.

“Be ready,” Galileo warned him.

The ancient one slunk away. He knew why Galileo was afraid, better than Galileo himself. He bowed under the weight of it.

Galileo often wrote to Picchena asking for Cosimo’s permission to go to Rome. By the middle of 1613, the reasons for these requests became more evident. His detractors had grown more vehement in direct proportion to his growing fame. A good deal of this Galileo had brought on himself. A lot of people hated him for what they called his arrogance.

To his household that wasn’t quite right. They spent a fair amount of time discussing him, as one does any great power in one’s life. “He’s very defensive,” La Piera would say. “So defensive that he attacks people in self-defense, and thus he becomes offensive.”