"This spirit fire is produced by cultivators who practice fire-attribute cultivation arts. They draw on the fire spirit energy within their bodies and burn it to refine pills, so it depends on the level of their cultivation. If a low-level cultivator cannot sustain enough fire spirit energy to finish refining a pill, the ingredients could go to waste at any moment. That is why low-level cultivators almost never refine pills," Senior Brother Liu Hang explained calmly. "Apart from that, there is controlling the intensity of the spirit fire. You must understand that these Heavenly Materials and Earthly Treasures are mostly plants. Some readily yield medicinal liquid when heated, while others do not. This requires an alchemist to understand the medicinal ingredients and exercise delicate control over the spirit fire."
"Mm." Li Xiaoya watched Senior Brother Liu Hang's every movement without blinking and listened intently. Suddenly, a question occurred to him. "Then why must we use spirit fire to refine pills? Won't other kinds of fire work?"
"That is because we Immortal Cultivators cultivate by absorbing Heaven and Earth Spiritual Qi and converting it into the spiritual power we need to improve our cultivation. But the speed and process of advancing through absorbing Heaven and Earth Spiritual Qi alone are far from sufficient, so we Immortal Cultivators take pills to improve our cultivation quickly. Most of the Heavenly Materials and Earthly Treasures used to refine cultivation-enhancing pills grow in places rich in Heaven and Earth Spiritual Qi. The longer they grow, the more Heaven and Earth Spiritual Qi they contain. Yet we cultivators cannot consume these Heavenly Materials and Earthly Treasures directly, because the spiritual power within them is too mixed and too overbearing. That is why alchemy came into being: it uses the mutually reinforcing and counteracting properties of these