In Maoshan Shu, the seven passes refer to Yunken Pass, Shangxian Pass, Zichen Pass, Shangyang Pass, Tianyang Pass, Yusu Pass and Taiyou Pass, which correspond to the seven stars of the Big Dipper (Greedy Wolf, Jumen, Lucun, Wenqu, Lian Zhen, Wuqu, and Pojun), and the seven passes represent the flow of vitality in any urban or rural or population concentration area.

To find the seven levels on the ground, first of all, the stars should be gazed, the Big Dipper circulates the North Star, rotates once a year, and there will be a slight change in the position every day, but the amplitude is very small, the change of the Big Dipper in the nine days is the minimum degree of displacement that can be seen by the naked eye, so in the Maoshan operation, the nine days is a stargazing cycle, and this cycle becomes the "number of Chongjiu" in the Maoshan operation, as long as you find a reference object on the ground to observe from a fixed angle and mark the scale, it is not difficult to determine.

The displacement of the Big Dipper is caused by the rotation of the earth, and the position of the earth changes, which gives the illusion of the change of the position of the Big Dipper. The human body is affected by this, looking at the Big Dipper at different times, the brightness of each star is different, but stargazing must conform to the principle of the number of Chong Jiu, the number of Chong Jiu is not only the stargazing cycle, but also the change cycle of the position of the seven levels of a place, within nine days, the position of the seven levels remains the same, and the direction of the qi veins remains the same, so the last day of the number of Chong Jiu is the best time to perform the Maoshan technique.

When the brightness of the Big Dipper changes, the direction of the local seven levels can be deduced according to the algorithm of the "General Principles of the Heavenly Evolution Bureau" in the Maoshan technique, such as the greedy wolf and the giant gate are bright and dark; Lu Cun, Wenqu, and Lian Zhen began to be dark and bright; Wuqu and breaking the army began and ended, then Yunken Guan placed the cadre position, Shangxian Pass, Zichen Guan set Xun position, Shangyang Guan set the position, Tianyang Pass placed the earthquake position, Yusu Pass to the Gen position, and Taiyou Pass placed the Kan position, just like the formula, so permutations and combinations, a total of 181 kinds were listed in the "General Principles of the Tianyan Bureau", which basically covered all the permutations of the light and shade changes of the seven stars. (Stargazing is the closest doctrine to the Sutu school of Maoshan Shushu, and this is only one of the branches of Maoshan Shushu.) ）