Under Joshi's tutelage, Chang-li's attempts with a sword became less hacking and slashing, more elegant cuts and swoops. They added an hour of sword practice to every cultivation session. The extra time spent resting seemed to help Hiroko. She perked up as they made their way deeper into the tower.

Chang-li wasn't sure, because there was no way to tell time in this place, but he felt as though they were going more than a day between purification tablets. They took one every fourth meal. With two or so hours spent cultivating around meal times, an hour of sword practice, snatches of actual sleep here and there, and interminable plodding through the vast wilderness of this first floor of the cultivation tower, time seemed to have lost all meaning.

Chang-li perused the entries in the cultivator journal. Scribe Wulan mentioned a similar thought: We have been journeying through this vast emptiness for untold days, weeks, perhaps months, and yet I sometimes feel it has been only a matter of hours. Who is to say if time runs slow here? On none of my previous trips inside a cultivator tower have I encountered such, but this is the first time I have spent day after day inside a tower without returning to the outside. It is forbidden by imperial law, after all.

After translating that excerpt, Chang-li uneasily broached the subject with his companions. "Are there rules about how often a cultivator should leave a tower?"

The former slave frowned. They were walking through the sands, the sky overhead yellow and red, heading for a dark spot on the horizon that was probably another oasis. "Access to towers is strictly controlled by the army and whichever sects they have chosen to lead an expedition. The monks of Hapiru told me I would be lucky to spend more than three or four days at a stretch inside a tower. That's not all bad. If we were able to return to the outside world and spend dedicated time cycling under the supervision of cultivation masters, we would no doubt be making breakthroughs."

"As compared to being here cultivating day and night?” Chang-li asked.

Joshi hesitated. "Perhaps not. We are all progressing far faster than the monks ever gave me to suspect. Especially you. I believe you must have a hidden gift for cultivation. It would be a shame if you were forbidden from continuing your climb."

Chang-li felt a flush of embarrassment. He was certain his advancement had to do with his cycling of violet lux. He was now deliberately cycling the violet lux through his channels using a technique he had deciphered from Wulan's notes. He coated each of his lux channels in turn, especially the ones leading to each of his arms. Scribe Wulan described how to weave the violet lux in with the particular color of lux most desired for a channel. So Chang-li was carefully laying down violet and orange through his left arm and fingers, and violet and yellow in his right. The rest of his body he left undifferentiated.

He knew he was seeing results the first time he made a ball of flame dance on the palm of his right hand. It lasted for only seconds before vanishing, but he could feel it there, distinct from the rest of him, feeding off his lux.

The secrets he was hiding from his companions were beginning to weigh on Chang-li's conscience. He cleared his throat. "The entry I just read in Scribe Wulan's journal made me wonder if perhaps somehow time passes differently for us inside a tower than it does outside. Perhaps the days we've spent in here might be only hours on the outside."

"How could that be?" Hiroko frowned. “I’ve never heard of anything like that.”

Joshi shook his head. "Nor I. Yet this tower is clearly larger on the inside than it is on the out. We've walked miles. Even accounting for how broad the base of the mountain is, we would have reached a far wall if there were one. So why should time not also run differently?"

"I hope that's the case," Hiroko said. "When the Dowager Pearl in charge of this Court of Gems believes I am dead, she will send word to the palace. My father will hear, and they may send a replacement bride for young Master Feng. They'll likely send a Blue princess. I need to return before that can happen."

"You're much better off without Feng," Joshi growled.

Hiroko chose to ignore him. The dark spot on the horizon heaved up and became a cube, sharp edges dark against the sky. They halted, studying it.

"Well?" Joshi asked. "What does your book say?"

"It describes several ruins they came across,” Chang-li said. "The first two, they thought, were empty. In the third, they discovered a riddle. It granted them a trophy like the ones at the oasis."

"Without having to fight?"

Chang-li nodded. "Correct."

"What sort of trial?" Hiroko asked.

"Unfortunately, Scribe Wulan did not describe it."

"Of course he didn't," Joshi said.

They crossed the sands till the cube reared over them. It was twenty feet tall, the same distance along. Around it was a vast, flat, black stone field, a quarter mile in width. Joshi set a hand on the stone. "I don't feel any lux workings." He took ten strides in, then sat down. "We should rest, eat, and cycle before entering."

"Good idea," Chang-li agreed, taking off his pack and passing around rations.

The cube loomed over him as he tried to cycle. He kept losing his pattern. Finally, he switched to the first cycling technique Joshi had taught him. Within its comfortable rhythms, he found himself at ease.

Moments later, something in his core shifted. He stopped cycling, prodding at it with his lux sense, then swapped to his lux sorting technique, allowing only orange, yellow, and violet lux into his core. It was denser, bigger, like he could shove more lux into the same core.

He had taken a concrete step toward Bodily Refinement.

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Joshi cracked an eye. "I felt that.”

“My core condensed." A smile spread across Chang-li’s face.

"Good," Joshi said. "The monks recommend doing that at least three times before reaching the Peak of Bodily Refinement."

Chang-li’s good mood vanished. Twice more. They had used up more than half of their purification tablets, and neither of his companions had reached even this first step of condensing. Chang-li was uncomfortably aware of the pressures on them. They must reach Bodily Refinement or find an exit to this place before they ran out of purification rations. Otherwise, the lux would drive them mad, like a towerbeast suffused with too much lux.

Uneasily, he joined his companions in a brief hour or so of sleep. When they rose, they circled the cube. On the far side was a door, a mere hole leading into the black interior. Joshi led the way without hesitation.

The inside of the cube was darkness. Chang-li summoned a ball of yellow lux fire to his hand. It winked out after a mere three heartbeats. He called it again. Its flickering light cast shadows on the smooth walls of the passage. Joshi plunged forward, seemingly uncaring of the darkness.

Then, as they stepped through the passage into a chamber, light flared all around them. Chang-li let his lux drop. The chamber seemed to be as square as the outside of the cube, but only about ten feet in every direction. In the center of the room were three pedestals holding basins, one raised above the other two. The tallest of the pedestals was about chest height. The light emanated from the walls, a gentle glow more blue than yellow.

Joshi prowled the corners of the room, running his hands along the wall. "No other exits. I'm not sensing any active lux in this building, but I do feel lux conduits running to those basins.”

Chang-li stepped up. The basins were white as bone and warm to the touch. Hiroko peered into one. "They're empty. Perhaps we're supposed to fill them.”

“With water?" Chang-li groaned as he thought of how far it was back to the previous oasis. Even if they had some way of carrying enough water to fill these, it would be a time-consuming business. Perhaps that was the challenge: to struggle across miles of wilderness lugging the water it would take to fill these bowls. Every drop in his canteen would be no more than an inch in a single basin.

"That can't be it," Joshi said. "This is a cultivator challenge, not a porter challenge."

Chang-li crouched. His eyes had caught something, a series of scratches on the face of the tallest pedestal. He ran his fingers along them. Yes, deliberate scratches, making a pattern. He couldn't quite make it out against the darkness of the stone.

Chang-li opened his satchel and pulled out his scribe's kit. He prepared his ink tray, grinding the stick down before adding a little water and mixing the ink. When he had thoroughly coated the surface of the pedestal, he took a scrap of parchment from his bag and pressed it carefully, rubbing hard against it. Then, holding his breath, he peeled it away. Dark lines stood out on the parchment. Characters in the scribe's script.

Hiroko clapped. "Well done. What does it say?"

Chang-li scanned the characters. "Test of lux purity. Each bowl to be filled with a different color of lux, without contamination from other colors. Highest value lux in the center bowl."

"How can we fill a basin with lux?" Hiroko asked. "It won't stay there."

"Perhaps they have been designed for it," Joshi eyed the two smaller pedestals. "These appear to be the same height, so does it matter what color we put in them?"

Chang-li shook his head. “Just the highest value in the middle. What does that mean?”

“Red, yellow and orange are Physical lux. They represent the lowest tier. Green is called Mental lux even though it usually is for healing spells,” Joshi said. “Blue, Indigo and Violet are the Spiritual luxes, as they affect the deepest nature of the world itself. So, Blue is the highest we can manage between us.” He turned to Hiroko. "Try channeling blue lux into the center bowl. Use the Swirling Mists technique that we’ve all practiced, but retain everything else inside yourself. Do you think we should fill the other two with orange and yellow, or will red be fine for one?"

Chang-li considered. "Let's try having you fill one with red lux. I'll put yellow in the third." He stepped over and began his cycling technique. He siphoned yellow lux into his right hand, then, holding his hand above the basin, pushed the lux out of himself. He couldn't see the lux leaving his body, but after a moment he could tell the basin had changed. Now it took on a slight golden hue.

"It's working."

Hiroko took up a place in between him and Joshi and began to cycle blue lux. They stood there, draining their lux into the basins. The colors grew deeper and deeper, creeping up from the bottom of the basin along the side. At last, just as Chang-li felt he could cycle no more, the last portion of his basin's edge turned bright golden, and he heard a soft chiming in the key, in the note of yellow. He stepped back.

Joshi, too, was done. Hiroko's basin was deep blue in the bottom half, a paler shade in the top. Sweat dripped down her face. She held her wrist with her other hand, as though trying to force the lux out of herself.

"You can do it," Joshi said. "You're doing well. Keep at it. Don't stop."

Her face showing the strain, Hiroko kept channeling. Chang-li's heart pounded as he watched. Somehow he knew if she stopped channeling the lux before the basin was full, they would fail the challenge. At last, the blue tinge suffused the entire basin. A note chimed. Hiroko sagged and started to fall. Joshi caught her under her arms and helped her to a seat against the wall. She nodded thanks.

Light shot upward in the color of each bowl. The three beams merged together, twisting into a brilliant column of white. It became a spot, five feet up in the air, a ball of white light, growing in intensity, stronger and stronger, until Chang-li could not look at it. He looked away, just as it flared even brighter. For a second, he could see nothing. Then his vision returned, purple splotches in front of his eyes. He blinked them away.

A glowing blue stone hovered in the air over the top basin. Chang-li stepped forward and took it. It was about an inch around and heavy enough to surprise him. The stone was warm to the touch. It seemed to be made out of the same substance as the bowls. He held it up to show the others. “Challenge completed."

"Well done," Joshi said. "I think we should take a rest. It's nice to be in, out of the view of that sky, don't you think?" He exchanged a glance over Hiroko's head with Chang-li, who understood what he meant. Hiroko needed time to recover.

"Sounds good to me.” Chang-li stowed the token away in his satchel and sitting down. He began to cycle, concentrating, as before, on his core.

Hiroko struggled upright. "I'm going to cycle for a bit before I sleep. I've seen the two of you. You're working hard to improve. I'm holding us back."

"We are progressing together," Joshi said gravely. "We have passed three challenges. We have time yet."

"I will not be a burden," Hiroko said. "I can stand on my own two feet. I know you think I am a spoiled noble."

Joshi's face twitched. “When I first saw you, as your palanquin bearer, I would have been surprised to hear you make that claim."

"I never wanted to ride in a palanquin," she said quietly. "I have been kept away from the world in a perfumed palace and carefully tended gardens. It was my duty and my role and my honor, but I have always longed to see the real world for myself. I used to dream, as a little girl, of dressing in servants' clothes and stealing out beyond the gates of the palace to see how they lived. I expect I had a rather more romantic notion of their lives than the reality. I never thought of hunger and sickness… But this chance to see how a cultivator lives, to more understand what they go through, it's beyond valuable for me. I will be far better able to understand the cultivator that I eventually wed and the others in his orbit whom I am supposed to help."

"You are not a burden," Chang-li assured her. "You have already saved my life. You have weathered every obstacle alongside us. I am glad to have you with us."

She smiled. "Thank you."

“Now,” Joshi said, "We should rest. We have another four trials yet to undertake."