Experiment

Xilai looked at Wuyi and spoke, "Why don't you try to use Qi to get the herbal wash again."

"I'd be able to do more, but I lack energy," said Wuyi, scratching. "Herbal wash, please?"

Xilai looked out from the tapestry. "Nice new window," he said. "If the Qi around here is insufficient, get your power elsewhere. You know how."

"From the fort array?" Wuyi asked. 

"How about the sun? The righteous or demonic Qi—everything is just energy. I think you know that already. If you already understand, you should know some sources are limited and some sources are unlimited. The sun, for example, is a good source of energy. The celestial bodies at night are also good sources of energy."

"How am I supposed to use the sun?" Wuyi said. "I know of no cultivation method that grants energy from the sun."

Xilai wasn't looking at him. He was looking out over the fields. "Do you trust me, boy?"