“Well?” she said.

“I pulled them apart. I kept them from fighting.”

“And why were they fighting? Why were they angry?”

“They were angry people. Choleric. They had so much yellow bile in them that if you pinched them your fingers would turn yellow.”

“Nonsense,” Hera said. “You know better than that. They were people just like you. Except that their minds were crimped, every day of their lives. Women in a patriarchy, what a fate. You know what I would have done if I were them? I would have killed you. I would have poisoned you or cut your throat with a kitchen knife.”

“Well.” Galileo regarded her uneasily. She towered over him, and her massive upper arms were like carved ivory. “You said that a time’s structure of feeling has a lot to do with how we are. Maybe you would have felt differently.”

“All humans have an equal amount of pride,” she said, “no matter how much it gets crushed or battered.”

“I don’t know if that’s true. Isn’t pride part of a structure of feeling?”

“No. It’s part of the integrity of the organism, the urge to life. A cellular thing, no doubt.”

“Cellular maybe. But people are all different.”

“Not in that.” She looked down at the screen in the pad on her lap. “There’s another trauma node near that one. This area of your amygdala is crowded.”

“But we seem to be approaching Io,” he pointed out hopefully.

Hera looked up. “True,” she said. She took her celatone from his head, which took a great weight off his shoulders. She patted him on the arm, as if to indicate that she still liked him despite his primitive circumstances and instincts. She even pointed out to him various features of her home moon as it grew to a fiery spotted yellow ball, floating before the great sunlit side of Jupiter. Both spheres were florid arrays, but their colors were different in tone, and mixed very differently over their surfaces. Jupiter was all pastel bands, its viscous eddies embroidering every border with gorgeous convolutions, like the side of a cut cabbage; while Io was an intensely sulfurous yellow ball, spotted by random spatter marks—mostly black or white or red, but including a broad orange ring around a whitish mound, which Hera said was the volcano massif called Pele Ra. She pointed out to him the shadow of Io on Jupiter’s face, so round and black it looked unnatural, like a beauty spot pasted on.

As they approached this hellish little ball that was her hometown, a blue aura began flickering around them. “What’s that?” Galileo asked.

“We are getting closer to Jupiter, which generates immensely powerful magnetic and radiation fields. We have to create fields to counteract them, or else we would quickly die. Moving at speed causes the two fields to interact, creating the aura you see.”

Galileo nodded carefully. Because of his mathematics tutorial from Aurora, he was pretty sure he understood the phenomenon better than Hera did. Probably it was best not to point this fact out, but her lack of awareness of it irked him. “Like ball lightning,” he said.

“To an extent.”

“Like the sparks you can make if you rub two pieces of amber together.”

She gave him a look. “Quit it.”

They flew close over the surface of the tortured moon, past the volcanic continent Ra Patera, where she had taken him during his previous visit. There were red rings around several of the volcanoes; Hera explained these were their plume deposits. “There are about four hundred active volcanoes.” Once past Ra, they continued their descent over slaggy plains that were the basic Ionian color—a burnt sulphur, greened in some places like old bronze, and pimpled everywhere by volcanoes. Some of these were tall cones, others long cracks; some were white as snow, others black as pitch. There was no correlation between morphology and color, so that it was impossible to grasp the lay of the land. An occasional impact crater added to the topographic confusion, until in many areas Galileo found it hard to determine up from down. The different minerals the volcanoes cast out, Hera told him, in plumes or rivers of different heights and viscosities, accounted for their disorienting and hideous variety. Most of the moon’s surface was too hot and viscous to build on, she told him, or even to walk over. “In lots of places if you tried to walk you would sink right into the ground.” Only the high massifs of dormant giant volcanoes stood far enough above the magmatic heat to cool down, serving as rock islands in an ocean of crusted lava.

When they came over the anti-Jovian side of the moon, Hera maneuvered her craft downward, slowing it until she could drop them vertically into the middle of a small but deep crater, filled with a lake of liquid orange lava. As they drifted down to the level of the crater’s rim, Galileo had a closer view over the surface of the moon beyond the crater, lumpy beyond belief. The resemblance of the landscape to his concept of hell was amazing. He remembered now; this was the landscape in which he had seen his fiery alternative. Yellow plumes of sulphur fountained high out of bubbling orange cracks and arced up against the black starry sky, falling in slow sheets of spume away from the upright columns. He had heard that the inner crater of Etna was like this one, its floor a fiery orange lava lake, crusting over with black excrescences that folded under in steaming noxious vapors. In the Inferno, Virgil had guided Dante into Hell by way of Etna, using caves and tunnels unfilled with lava. Now his own amazing Virgil was leading him down onto the real thing. Their little craft, transparent to them, held them hovering over the burning lake.

“What will you do here?” he asked.

“I’m hiding, waiting for my friends from Ra. We’ve decided to arrest Ganymede and his supporters. Their base is on Loki Patera, and it’s not going to be easy to make our approach without them seeing us and taking flight.”

“You need to surprise them.”

“Yes.”

“Because you intend to imprison them?”

“Well, at least to keep them on Io. Disable their ability to leave. Because of the threats Ganymede made, the Synoekismus has authorized us to take such an action. In fact they demanded we do it. Since the Ganymedeans have set up a base on Io, the council can pretend they’re our problem. Leave us to figure out how to do it. It’s causing a bit of a tactical disagreement right now among my cohort.”

“This Loki Patera, is it an active volcano, with a lake of molten rock in its crater?”

“Yes indeed. It’s one of the biggest calderas of all, and these days it’s sending up quite a sulphur plume.”

“And the interior of Io, you said it’s melted through and through?”

“Yes, that’s basically right. The pressure makes the core a kind of solid, of course.”

“So chambers of liquid rock link up below the surface, or pool together?

“I think so. I’m not sure how completely the interior is understood.”

“Or explored?”

“What do you mean?”

“These craft of yours are self-contained, right? They withstand the vacuum of space, as we see, and the ocean of Europa. Is the lava of Io any different, in a way that matters to your ship?”

“It’s hotter!”

“Does that matter, though? Wouldn’t your craft withstand the heat, and the pressure?”

“I don’t know.”

“You could ask your machine pilot, it would know. And it has systems of reckoning to locate itself in space, isn’t that right?”

“If I understand you correctly, yes.” She was now tapping madly at her pad, head tilted to listen to something Galileo couldn’t hear.

“So,” he continued, “nothing would prevent us from sinking down into the lava chambers below some volcano near Loki, and traversing the channels down there until you could come up out of the erupting crater of Loki, thus surprising Ganymede in his refuge?”

Hera laughed shortly, with a look at him that seemed to contain a new surmise. “Those math lessons have made you ingenious!”