What are the Ten Gods (십신)?
Ten names for how each letter in your chart stands toward you.
In plain words
A Saju chart is eight letters. One of those eight is you — the upper letter of the day you were born, called the day stem (일간). The Ten Gods are the names for how each of the other letters stands toward that one. There are five kinds of standing: what stands where you stand, what you make and send outward, what you handle and hold, what presses you into a shape, and what feeds and raises you.
Each of the five splits again by whether its yin-yang matches yours or not. Five times two is ten, and those ten are the Ten Gods. You do not have to memorise the names first. The ten collapse back into five plain sentences: friends who are also rivals (비겁), what you make and show (식상), what you hold in your hands (재성), the frame you sit inside (관성), and what feeds you (인성).
How Bokki computes it
The reference point is always the day stem, and only two things decide a name: how your element stands to the other element, and whether the yin-yang matches. Same element, matching yin-yang gives 比肩; same element, different yin-yang gives 劫財. The element your day stem generates gives 食神 and 傷官. The element your day stem controls gives 偏財 and 正財. The element that controls your day stem gives 偏官 (also called 七殺) and 正官. The element that generates your day stem gives 偏印 and 正印. That is the whole rule, and in Bokki it is six lines of code.
The Ten God on each pillar's upper letter comes straight from the perpetual calendar. On top of that Bokki measures force — how much weight has piled up in each of the five groups. A letter is not one vote. An upper letter counts 1. A lower letter is split across the stems hidden inside it: 子 is Water 1.0, while 丑 is Earth 0.6, Water 0.3, Metal 0.1. The month's lower letter gets three extra multiples, because the season is the chart's centre of gravity. If three lower letters form a full trine (삼합) their element gains 3 more; a half trine that includes the cardinal branch gains 1.5.
A worked example, run through the actual code. Born 15 May 1990 at 14:30 in Seoul, the four pillars come out 庚午 辛巳 庚辰 癸未. The day stem is 庚, yang Metal. The year's 庚 is the same Metal with the same yin-yang, so it is 比肩. The month's 辛 is the same Metal with the opposite yin-yang, so it is 劫財. The hour's 癸 is the Water that Metal generates, opposite yin-yang, so it is 傷官. Measured as force, that chart reads officer 46%, companion 30%, resource 14%, output 8%, wealth 3%.
What we do not compute
We do not spell every lower letter out into Ten God names. The letters hidden inside a branch are counted as elemental weight only; we do not attach labels like “the Ten God of the middle hidden stem of your day branch.” Attaching a name means being able to defend it, and our calculation does not reach that far yet.
The hidden-stem weights (0.6 / 0.3 / 0.1) are not the exact day-shares of 월률분야. They keep the order right — which hidden letter is heaviest — but they are not a claim about how many days each one rules. Our source says so in the same words. It is a symbolic weight, not a score.
And we do not rank the Ten Gods as good or bad. “You have 七殺, so your road is rough” or “you have 正官, so you are destined for office” are sentences Bokki does not write. We name the seat; we do not grade the person.
Closing note — two questions decide all ten names
Put simply: every one of the ten names comes from asking two things about a letter — which of the five relations it holds to your day stem, and whether its yin-yang matches yours. Run the 1990-05-15 chart above and the year stem sorts into 比肩 while the hour stem sorts into 傷官, from the same six-line rule; weighed by force the same chart comes out officer 46%, companion 30%, resource 14%, output 8%, wealth 3%.
The weights are symbolic on purpose, not a claim to the day: an upper letter counts 1, a hidden stem takes 0.6 / 0.3 / 0.1 depending on how deep it sits, and the month branch alone carries triple weight. We stop short of naming every hidden stem and short of ranking any of the ten as lucky or unlucky — a Ten God says what a letter does, not whether having it is good news.