The words daycolor uses
Everything below begins with one plain fact: the moment you were born, the Earth sat at a particular point on its journey around the Sun, and the Moon at a particular point around the Earth. Your birth month, day, and hour are those positions — a small set of cosmic coordinates. Saju is the old craft of reading a life from them. None of it predicts or decides anything; it simply describes the season a life is standing in.
Cosmic coordinates year · month · day · hour
The Sun at the centre, the Earth and its Moon in orbit.
A calendar is really a way of naming orbits. The month marks where the Earth is on its year-long path; the day, the position the Earth and Moon hold in relation to each other; the hour, a single moment of the Earth's own turning — measured against the Sun and Moon overhead. Saju takes those same positions and writes each one as two Chinese characters. So your chart is not a mystical stamp — it is a set of astronomical coordinates, written in an old notation.
The Four Pillars 四柱 · saju
Saju means "four pillars." Your birth year, month, day, and hour each become one pillar, and every pillar is written with two characters — one Heavenly Stem above and one Earthly Branch below — so a full chart is eight characters. In Korean this chart is a myeongsik (명식). The stem of your day pillar is called the day master: it is the single character that stands for you, and the rest of the chart is read around it.
Yin & Yang 陰陽
Under everything sit two states — not good and bad, but two directions of one motion. Yang (陽) reaches out and rises; yin (陰) gathers in and settles. Almost every idea in saju is built by combining these two, again and again. Hold onto that: it is the same two-state logic that the hexagrams turn into a kind of binary, further down this page.
The Five Phases 五行 · ohaeng
The five phases (五行), often translated as the "five elements", aren't materials but stages of one flowing energy — like specks of gas and dust in space that gather, rise, and scatter like a fountain, then draw back together. It rises as Wood, radiates as Fire, settles and balances as Earth, gathers in as Metal, and condenses as Water — then returns to Wood. The balance among these phases is what a reading watches most closely.
The Ten Heavenly Stems 天干 · cheongan
There are ten stems — each one of the five phases in its yang (larger, outward) or yin (smaller, inward) form. Your day master is always one of these ten. The icons are the ones daycolor uses in the app.
The tall tree — upright growth that pushes straight up, the first plain force of life starting.
Grass and vines — soft, bending growth that finds its way around obstacles rather than through them.
The sun — bright and open, warming everything at once, hiding nothing.
A candle or hearth — smaller and steadier, warm up close, a light you can sit beside.
The mountain — broad, solid, slow to move; ground that has been here a long time.
Garden soil — soft and receptive, the quiet ground that actually grows things.
The sea or a great river — wide and always moving, going somewhere with force.
Rain and dew — quiet and gentle, reaching into small places nothing else can.
The Twelve Earthly Branches 地支 · jiji
Where the ten stems are the sky's own energy, the twelve branches are what that energy becomes once it reaches the Earth and answers the turning seasons — heaven above, ground below. That is why a chart's eight characters are read as two rows: stems reaching down, branches rising to meet them.
There are twelve branches — the twelve zodiac animals. Each carries a phase, a place in the year's seasons, and a two-hour slice of the day, which is why your birth hour matters.
The turning point of the year's dark, when days begin, invisibly, to lengthen again.
Cold, patient ground before the thaw — the slow hour that carries winter toward spring.
The first stir of spring, new growth pushing up while the world is still half-asleep.
Spring at its softest and fullest, when green spreads quickly and easily.
Damp, rich ground where spring gathers energy before the heat of summer.
The first real warmth of summer — bright, quick, and rising.
Noon, and the height of the year; fire at its most open and outward.
Warm, dry earth as summer settles — the pause before the turn toward autumn.
Dry ground at dusk, holding the last warmth as the year closes in.
The first deep quiet of winter, when everything draws inward to rest.
The Ten Stars 十星 · sipseong
Once the day master is set, every other character has a relationship to it. Saju gives those relationships ten names, the Ten Stars (also known as the Ten Gods, 十神) — roles rather than fortunes, like support, output, wealth, and authority. daycolor draws on them when it reads how a chart is put together.
The Luck Cycles & the Year 大運 · 歲運
A chart does not stand still; larger cycles turn around it. The Great Luck Pillars (대운, daeun) are long seasons of about ten years each, moving in order through the stems and branches. The Annual Pillar (세운, seun) is the character-pair for a single year. daycolor shows both, so you can see which season a chart is passing through now.
The Hexagrams — an extended binary 周易
The verses in daycolor draw on the I Ching, and its sixty-four hexagrams are easier than they look. Start again from yin and yang. Draw a line: an unbroken line is yang (1), a broken line is yin (0). That is one bit. Stack six lines and you have 2 × 2 × 2 × 2 × 2 × 2 = 64 — the sixty-four hexagrams. Tap the lines to change them.
That symbol (䷀) is exactly how daycolor writes a hexagram. So the I Ching is not a vague mystery; it is an early base-2 language, a way of describing every state of change with two marks. Leibniz, who helped invent modern binary, noticed the same thing three centuries ago. To read all sixty-four in full, open the 64 Hexagrams one by one.
The Jiaoshi Yilin 焦氏易林
The I Ching gave each hexagram a single line of judgment. The Jiaoshi Yilin — "Forest of Changes", by tradition the work of Jiao Yanshou (焦延壽) in the Han dynasty — goes a step further. It takes each of the sixty-four hexagrams as able to change into any of the sixty-four, and sets under every one of those changes a short verse, chanted four characters at a time.
Hence 64 × 64 = 4,096 verses. Each is named 'A之B' — hexagram A going to hexagram B. From the same starting hexagram a wholly different scene opens depending on where it goes, and there is a verse even for the case of staying put (A之A).
The verses are closer to scenes than to verdicts: they hand over a picture rather than pronounce a reading. Every line of verse daycolor offers comes from here.
So beside each verse daycolor sets not a verdict of fortune or misfortune but a word for its grain: with the current where the scene runs smoothly, sun through rain where it is a hard one, both at once where the two sit in the same verse. Even a hard verse has a place where the light gets in; the words are there to read what is present before what is lacking.
Jikil 直日
A verse of the Jiaoshi Yilin is written 'A之B'. A is the hexagram that keeps the day; B is the hexagram it changes into by a single step. So before any verse can open, one has to know whose day today is. That is jikil (直日).
The old scholars stood four hexagrams — 坎, 震, 離 and 兌 — at the winter solstice, spring equinox, summer solstice and autumn equinox, and shared the year out evenly among the remaining sixty, about six days to each. Which hexagram falls in which solar term is handed down as a table; daycolor follows the arrangement set out by Lee Bong-jo (이봉조, 2013).
The awkward part is that a year is not 360 days. Six days for each of sixty hexagrams makes 360, and how to share out the five-odd days left over was disputed even among the Han scholars; Jiao's own method has not come down to us. So in practice one draws up a date table for some one year and adjusts it against an almanac each year after.
daycolor does not memorise a table; it measures the sky again every year. It computes the moments at which that year's solstices and equinoxes arrive and sets them as four pillars. Each of the four hexagrams keeps the head of its pillar for a little less than a day, and the fifteen that follow divide the time to the next pillar equally. No day is left out and no hexagram is skipped, and the small yearly drift of the solar terms is carried just as it is. Even this shows through: a hexagram's turn runs a little under six days in winter and a little over in summer — because the Earth moves faster in winter, when it is nearer the Sun.
At the same moment on the same day, the hexagram keeping the day is the same for everyone. What differs from person to person is B — which of the six lines is moved by a number drawn from one's own saju together with the stems and branches of that day. The six hexagrams each one can reach in this way are listed on its page in the 64 Hexagrams.
The year's Annual Pillar (세운) is added into this number as well, and it follows the calendar year, turning over on 1 January. The year pillar of the chart itself turns at Ipchun (立春, the Start of Spring, in early February), as saju convention has it — so from early January until then the two can name different years.
A note
In daycolor, even the pictures travel from sky to ground: each reading begins far out in the cosmos and settles toward the earth, imagining a different scene at each step down.
And a small honesty — this is one telling, not the only one. Saju and the I Ching hold many schools and quiet disagreements. This service began, plainly, from a student's notebook — its margins full of doodles made while reading through those competing ideas. So enjoy what's here and think with it, but treat it as a sketch, not doctrine. If it sparks real curiosity, the deeper study is well worth doing on your own.