Order, rule, the measured step: the name Tiandao
The name is the plainest of the 24. Heaven's way is the order things keep when nothing forces them: the seasons in sequence, the stars on their circuit. The school reads only that into Tiandao: sequence, rule, keeping to the line.
On a hillside that image becomes a test of regularity. A range that steps down in even beats, a peak that stands square and upright, a stream that keeps its bed: these keep the way. A ridge that lurches, a peak that tilts, a stream that breaks out across the fields do not, and Tiandao has nothing to witness there.
Tiandao as the school's witness for a Gui range, peak or stream
Gui is a thin slice of the compass between Zi and Chou, so the school reads it with care. When the incoming range enters the site on Gui, the master walks back along the spine to see whether the knots come in order: rise, narrow, rise again, then settle. Orderly arrival is what Tiandao answers to. A peak standing on Gui is read as an upright attendant on the north east shoulder of the seat; water arriving from Gui should follow one channel and come in steadily.
In the Cuiguan Pian, dragon, cave, sand and water each have a star to answer to; for Gui it is Tiandao. An ordinary star only answers: a broken range on Gui is still a broken range.
What this means on the ground
On the Tianxing ring of the school's luopan, Tiandao sits one step clockwise from Tianlei, under the character Gui. Set the plate level behind the headstone, or inside the threshold of a house or shop, and take the sitting line three times with no steel nearby. Then sight each peak and the water mouth and write down the bearing. Anything from 7.5° to 22.5° is on Gui and is marked as Tiandao.
In a town the same line is read across the door. A regular row of houses, a straight fence or a steady street on that bearing keeps order; a demolition gap, a leaning tower or a slip road cutting across does not.
Common mistakes
Gui is where small errors show most. A phone compass left on true north can shift a peak by ten degrees or more overseas, enough to move it from Gui onto Zi or Chou. Use the magnetic needle on the luopan itself.
Do not turn the name into a verdict. Heaven's Way means order, not that a site is favoured. Do not count stars before walking the range; a tidy reading on the ring is worthless if the ridge behind it has been quarried. And do not take bearings off a map or satellite image, drawn to true north with no slope.
Questions people ask
Which star sits on Gui mountain?
In the Tianxing school, Gui mountain at 15° north north east, between Zi and Chou, carries Tiandao, Heaven's Way. It is an ordinary star whose name means order, rule and keeping to the course.
What does Tiandao mean for my house?
If a hill, building or road stands on 7.5° to 22.5° from your front door, the school checks whether it is regular and upright. If it is, Tiandao confirms an orderly support on that side. If it is broken or crooked, the star does not improve it.
Is Tiandao a noble star?
No. The four noble stars are Tianhuang, Tianshi, Taiyi and Shaowei. Tiandao is one of the ordinary stars, and Gui is not among the three auspicious or six elegant mountains either. It confirms the landform and nothing more.
Have Master Zhang read the Tianxing ring at your site, or learn to set the plate yourself on the field course in Ganzhou.