Half trine

Meaning

A half trine is two branches of a trine, one of them its peak: the birth and the peak, or the peak and the storehouse. Shen and Zi lean towards Water, and so do Zi and Chen; Hai and Mao, Mao and Wei towards Wood; Yin and Wu, Wu and Xu towards Fire; Si and You, You and Chou towards Metal. Eight pairs in all, each holding the heart of its phase, Zi, Mao, Wu or You, with one of its two companions.

The tradition reads it as a partial alliance. The two branches pull the same way and give their phase some weight in a chart, but the triangle is open: the phase is a direction the chart tends towards, not yet a force it holds. The missing branch can come later, from a luck pillar, a year or even a day, and close the triangle for as long as it stays.

The peak matters. Two branches of a trine without it, the birth and the storehouse, Shen and Chen or Yin and Xu, are a weaker bond: some schools call it an arch around the missing peak, others no bond at all, and Ulune does not count it as a half trine.

In practice

• In BaZi: Ulune names a half trine between two pillars, with the phase it leans towards and whether the pillars stand side by side, and says plainly that it does not transform on its own.
• In time: when a luck pillar, a year, a month or a day brings the missing branch, Ulune reads the whole trine it completes with the chart’s two branches, and its phase, for that time.
• Two charts: between two people’s pillars, two branches of one trine count as a meeting of their own, an alliance between the two charts.
• The zodiac does not split trines in two: any two animals of one triangle are allies there, the year’s, the month’s, a person’s or two people’s.

Across traditions

• In Western astrology two planets 120° apart make a trine, and a third at the missing corner makes a grand trine: the same step from an open bond to a closed triangle, read as ease growing into a gift.
• In Indian astrology Jupiter casts a special glance on the fifth and ninth signs from its own, the trine positions, so that a single planet can open the triangle that two others close.
• Feng Shui’s Three Harmonies school, one of its great schools of land and water, reads the course of streams by the same birth, peak and storehouse on the compass, as water enters at one point of a trine and leaves at another.

Origin and history

The halves come from the course of each phase that the Huainanzi described in 139 BC, born in one branch, at its height in a second, gathered in a third. Of the three, the peak was always the strongest, one of the four cardinal branches in the heart of a season, and the classics of the Zi Ping school made it the condition of a half: a phase leans only where its heart is present.

The Yuanhai Ziping and the San Ming Tong Hui name the halves beside the whole trines, and later masters argued over their force. The Di Tian Sui and Ren Tieqiao’s commentary judge every combination by the season and by what stands around it; the Ziping Zhenquan asks of every combination whether it is strong enough to change a chart’s structure. The arch between birth and storehouse, without the peak, has remained a point of debate.

How Ulune calculates it

A half trine is two different branches of one trine on two pillars, one of them the trine’s peak: Zi, Mao, Wu or You. When all three branches of the trine stand in the chart, Ulune names the whole trine instead. A half trine is never read as its phase on its own; between neighbouring pillars it is flagged as side by side. In time, Ulune counts only whole trines, completed by the pillar that arrives, and between two people’s charts any two branches of a trine.

Correspondences