Why does "clearing the capsule" become synonymous with Feng Shui?

Why does "clearing the capsule" become synonymous with Feng Shui?

Guo Pu, a native of the Eastern Jin Dynasty, became the pronoun of "Feng Shui" or "integrity" in ancient times. Guo Pu (AD 273-324), born in Wenxi, Hedong (present-day Shanxi), was a famous scholar and Taoist master in the Eastern Jin Dynasty. It is said that Guo Pu got nine volumes of books in Huang Shigong's green bag, thus mastering the five elements, astronomy and divination, and wrote the classic book Buried Book. This book covers the heavens and the earth and is extensive and profound. "There are five stars in the sky, five elements on the ground, stars in the sky, mountains and rivers on the ground, qi on the ground, beautiful scenery in the sky, and the discipline of establishing people is extremely purple."

Huang Shigong's Qingnangjing, which has been handed down now, is divided into three volumes, the upper, middle and lower, and the full text is only 4 10.