Our journey toward understanding humanity’s past, present, and future begins with the principle of the Cosmic Year. Western philosophy and science have largely treated time as linear, but Jeung San Do cosmology understands time as cyclical: the universe unfolds according to a repeating rhythm analogous to Earth’s year.

Each Cosmic Year spans 129,600 years and consists of four cosmic seasons—cosmic spring, summer, autumn, and winter. The first two seasons, spring and summer, together form the era of the Early Heaven, while autumn and winter constitute the Later Heaven.

The Early Heaven is the age of growth accompanied by suffering. It is the period in which heaven and earth give birth to and nurture humanity, yet it is governed by the principle of sanggeuk (“mutual conflict” or “mutual restraint”). All existence develops through division, competition, and struggle; continuous tension and conflict drive the maturation of life.

The Later Heaven, by contrast, is the age of maturation and rest. During this era, conflict comes to an end as sanggeuk gives way to sangsaeng (“mutual life-giving” or “mutual beneficence”). Harmony prevails: nature and civilization come into unity, humans and spirits coexist, human dignity is fully realized, and the imbalance of dominance yields to the equality of yin and yang.

At the turning point from cosmic summer to cosmic autumn—from Early Heaven to Later Heaven—Sangjenim incarnated in this world to guide humanity and the spirit realm safely through the transitional period known as the Later Heaven Gaebyeok (the Autumn Gaebyeok), leading toward the long-awaited Later Heaven world of immortality.