Taoist retreat is to find a cave in the mountains to retreat, so "entering the mountains" is retreat from the perspective of Taoist practice. In other words, don't close the door until you "repay Dan", or you will get severe rheumatism, short-lived illness or death. So it's not convenient to say anything here. Because if there is a teacher, I will tell you when I get to "Return Dan". Without my teacher's biography, I can't achieve it in my life, so it's meaningless to say that I'm closed to the outside world.
Closing the door means closing your heart, not being taken away by the outer edge and the inner edge, just being aware. It means blocking the pass and not communicating with the outside world. "Pigu" originated from "not eating grains" in Taoist health preservation, and it was a common way of health preservation in ancient times. It originated in the pre-Qin period and was popular in the Tang Dynasty. Also known as "Valley Valley", "Valley Valley Valley", "Valley Valley", "Valley Valley" and "Hugh Valley".