In the depths of the secular mortal world often had the thinnest Qi of vitality. Having spent such a long time in Qing Xuan, Shen Lian found it hard to adapt to the mortal realm again. The gains from his daily Qi cultivation were barely enough to keep his body pure and clean.
This was why the cultivators of Qi chose to retreat into the wilderness and the mountains and steered away from the secular mortal world. Unless absolutely necessary, they would not visit the secular mortal world.
The secular mortal world was not conducive for the cultivation of Qi, but was good for the cultivation of mind.
Techniques came from the heart, and with supreme wisdom, even a flower or a leaf could be the world. Then, one would not be restrained by whether one was in the secular world or otherwise.