A saju chart is often imagined as a fixed snapshot of the moment you were born — but saju also moves. Layered over that birth chart is the Great Luck cycle, a sequence of ten-year periods that every life passes through one after another. Each period adds its own heavenly stem and earthly branch over your natal chart, so your story unfolds as the fixed pattern of your birth meets a slowly changing season of luck. This is why two people born with the same chart can still walk very different roads: they may be moving through different decades of the cycle.
Where the cycle begins and which direction it runs is set by your birth — traditionally by the polarity of your birth year together with your sex, counted out from the month pillar. The first period starts at a particular age, and from then on each Great Luck period lasts about ten years before handing over to the next. You do not need the technical calculation to use the idea; what matters is that a life is read not as one fixed verdict but as a series of ten-year seasons, each with its own colour.
To read a period, its energy is set beside your Day Master — the central self of the chart. A decade rich in an element that supports and feeds your Day Master tends to feel like a following wind; one heavy in an element that drains or pressures it asks for more care and tending. And because the Ten Gods are defined by how each element relates to the Day Master, a Great Luck period also shifts which themes — wealth, work, study, relationships — come to the foreground for those years.
Over the slow ten-year cycle, a faster layer turns as well: the yearly luck, the energy of each passing year meeting the decade you are in, which in turn meets your birth chart. Timing in saju is this nesting of cycles within cycles — the year inside the decade inside the life. Reading them together is what lets a practitioner speak not only of who you are, but of when a season may be ripe for beginning, building or resting.
Seen this way, the Great Luck cycle is less a fixed schedule of fortune than a way to view your life in seasons — to notice that no single decade is the whole story, and that what feels like winter is part of a turning wheel. As always in FortuneLeaf, it is offered for reflection rather than as fate: a gentle map of timing that helps you meet each season of your life a little more clearly.