What the day master actually is.
Every saju chart has four pillars. Each pillar pairs a heavenly stem (천간) on top with an earthly branch underneath. The stem sitting on top of your day pillar is your day master. It's calculated from the date you were born, and it doesn't change.
That single character is the reference point for the whole chart. The other three pillars — year, month, hour — are read in relation to it. When a saju reader looks at your chart, the first thing they ask is which day master you are. Everything else is downstream of that.
Why ten and not twelve.
The Western zodiac has twelve signs because it's tracking the calendar months. Saju uses a different system on the stem side: five elements × two polarities = ten. Each of the five elements (Wood, Fire, Earth, Metal, Water) has a yang form and a yin form. That's the full set of day masters.
Element + polarity = personality.
The element tells you what material you're made of. The polarity tells you how that material moves. Yang is expressive, structural, outward — it pushes. Yin is adaptive, relational, inward — it shapes itself to context.
Take Wood. Yang Wood (甲) is the oak: it grows in one direction and asks the world to make room. Yin Wood (乙) is the vine: same element, same will to grow, but it wraps around obstacles instead of pushing through them. Same Wood, completely different temperament. Saying you're Wood doesn't actually narrow you down. Saying you're the oak or the vine does.
Why your day master isn't your whole chart.
The day master tells you what kind of self you have. It doesn't tell you what kind of life that self is moving through. That part comes from the other three pillars — year, month, and hour — and from the elements they bring.
A Yang Wood born in summer with a chart full of fire reads as bright, fast, a little burned out at the edges. A Yang Wood born in winter with heavy water reads quiet, deep-rooted, slower to act. Same day master. Different climate. The chart describes the climate; the day master describes who's standing in it.
How Given shows your day master.
Inside the app, each day master gets a Personal Essence archetype name — Yang Earth becomes The Guardian, Yin Water becomes The Oracle, Yang Wood becomes The Pioneer. The element and polarity stay mathematical and accurate. The archetype name makes them readable without a glossary.
You can see the original stem character, the element, the polarity, and the archetype on the same screen. None of it replaces the others. They're all describing the same thing at different distances.