A gate at the west south west
Shen is an earthly branch, the monkey, the hour from 3 to 5 pm, the start of autumn, element metal. It is the last of the three Kun trigram mountains, after Wei and Kun; its right hand neighbour at 255 is Geng, seat of Tianheng the Beam and one of the three auspicious mountains. Its opposite is Yin at 60 degrees. A gate is narrow by nature, so the star is most at home where the landform narrows: a water mouth between two hills, a gap in the guarding ridge, the lane that leads to a door. Where there is no opening on Shen there is nothing to guard, and the star simply records that the bearing is closed.
Reading the gate against the water mouth
Here the order is landform first, star second; that is the school's whole method, and the Cui Guan Pian sets the pattern by matching dragon, hollow, sand and water each to a star. Of the four, the water chapter is where Tianguan does most of its work. Walk to the water mouth and see whether it is locked: two hills closing on each other, a bend that hides the outlet, a rock or islet in the stream. If that lock sits on Shen, the star ring reads Tianguan and the gate image fits. If the mouth on Shen is wide open and the water leaves in a straight line, the star confirms an unguarded site. An ordinary star does not close a gate that the hills left open.
What this means on the ground
At a grave, stand behind the stone, sight along its face, then turn the plate to the outlet where the water leaves the valley. At a house or shop, stand inside the main door, back to it, and look out; note which way the drains and the street run off. Level the luopan, let the needle settle, read three times, no steel at hand. A reading between 232.5 and 247.5 falls on Shen, and the star ring slot above it says Tianguan. In town, the gate is the side road or alley mouth at this bearing: a narrow, well kept lane that turns before it reaches you is a locked gate, a wide straight street that drains the block is an open one.
Common mistakes
Mixing the two Tianguan stars. The Gate is on Shen at 240; the Office is on Yi at 105, and the characters are different. Reading the star off a phone, which has no star ring and is usually set to true north; abroad that can push Shen onto Kun or Geng. Taking the word gate as a forecast about the family's comings and goings. Counting stars before you have found where the water actually leaves. Picking the water mouth off a satellite image instead of walking to it.
Questions people ask
What star is on Shen mountain in feng shui?
Tianguan, Heaven's Gate, over 232.5 to 247.5 degrees, west south west. An ordinary star, read mainly against the water mouth or the entrance on that bearing.
Is Heaven's Gate the same as Heaven's Office?
No. Both are Tianguan in pinyin. The Gate uses the character for a pass and sits on Shen at 240; the Office uses the character for an official and sits on Yi at 105.
What is a water mouth and why does it matter here?
The water mouth is where the water leaves the site; the school wants it locked by hills or a bend. If it sits on Shen, Tianguan is the star over it, and it confirms whether the lock is there or not.
Book Master Zhang to walk your water mouth, or come to a Ganzhou field course and learn to find it yourself.