"Take care of your true fire. Don't make it gulp the earth fire." Xu Fu flicked an angry look at Ye Chen.

"True fire can swallow earth fire?" Ye Chen asked in surprise.

"Of course. They're both fires."

"It's my first time to hear this." Ye Chen mumbled and warned the true fire in his elixir sea. If it devoured the earth fire, Xu Fu would strangle him.

"Put your hands on the stove. I need to evaluate the rank of your soul." Xu Fu uttered.

"Rank of soul?" Amazed, Ye Chen knew the concept for his first time, albeit an information collector before.

He placed hands on the stove gently and wondered its ability.

Buzz!

The stove vibrated the second he put hands on it.

A trace of spiritual light rushed out from the stove top and transformed into the character--'spirit' aloft.

"Your soul ranks the spiritual realm!" Stunned, Xu Fu stroked his moustache.

Ye Chen withdrew his hands and cast a curious look at Xu Fu, "Sect elder, how to rank souls?"

"Souls are classified into five levels: human, spirit, Xuan, earth and heavens." Xu Fu continued his explanation, "The five levels correspond to the five stages of cultivators, the human realm parallels the Qi condensation stage, the spirit realm the human core stage, the Xuan realm the true Yang stage, the earth realm the virtual spirit stage, and the heavens realm the empty darkness stage. Generally speaking, the ranks of your cultivation base and soul should be the same. But your soul is one level higher than your cultivation base. "

Xu Fu squinted at Ye Chen, "Have you ever taken the medicine for nurturing soul?"

Ye Chen waved head gently.

"So weird." Xu Fu stroked his moustaches in confusion, "I've only seen those whose cultivation bases are higher than souls. You're an exception that I meet for the first time."

"Is any difference between those people and me?"

"Of course, there is. Soul is mysterious with many possibilities. The soul-ranked-high people possess extraordinary comprehension. They have an advantage to refine their core souls."

"What is core soul?" Ye Chen's eyes sparkled.

Xu Fu inhaled with a yearning and respectful look, "Core soul is one level higher than soul, just as spiritual force ranks higher than vital energy. Generally, only the cultivators reach the empty darkness stage, can they be qualified to refine core souls, which can live out of flesh. As long as the core soul is alive, the body encompassing it won't die."

Ye Chen rubbed his chin, "So the cultivators below the empty darkness stage could not refine their core souls?"

"Not really. Anything may happen in the world of wonder. It's rare for cultivators at the virtual spirit stage to refine their core souls. But such people exist."

After a brief pause, Xu Fu continued, "Some with extraordinary abilities live in the universe. I've read a secretive anecdote in an ancient volume. A mysterious and primitive clan was born with core souls."

"So awesome. What clan?"

"God Clan"

"God…Clan!" Ye Chen broadened his horizon today. Xu Fu's knowledge and experience went beyond his expectation.

"Your soul is one level higher than your cultivation base. You probably could refine your core soul when reaching the virtual spirit stage."

"I'm looking forward to it." Ye Chen chuckled.