丁 Ding
Yin Fire, the candle, the lamp, the hearth fire. A smaller, steadier fire that illuminates one thing properly.
What a Ding day master is
Yin Fire is focused where Bing is broadcast. It is the flame you read by, and it burns longer because it burns narrower. Ding people tend toward depth over reach: fewer relationships held more carefully, one craft rather than five interests.
In Chinese astrology your core element is Yin Fire, pictured as the candle flame. You are precise and warm, and you light one room completely. You change lives up close, not from stages.
Ding at its best, and where it strains
Strength. Sustained warmth and real attention. Ding notices the individual person in a way Bing rarely does.
Difficulty. A candle is vulnerable to weather. Ding can be extinguished by an environment that gives it nothing to burn, and it withdraws rather than flares when depleted.
Ding shares its element with Bing, the yang form of Fire, and the two behave nothing alike. That is the whole reason BaZi uses ten stems rather than five.
The four relationships every BaZi reading runs on
Your day master is not read alone. Everything else in the chart is judged by how it treats Fire, and the five elements move in two cycles: one that nourishes and one that restrains. For a Fire day master those come out as follows.
A chart with plenty of Wood and little Water reads very differently from the reverse, even with the same day master. That balance is what a BaZi practitioner is actually looking at, and it is why two Ding people can be unrecognisable to each other.
BaZi pillars here use the solar calendar the tradition uses, so the year turns at Lichun in early February rather than at the lunar new year, and the hour pillar follows the late-Zi convention.