Chapter One Hundred Thirty: The Four Seasons First Divide — Spring, Summer, Autumn, Winter

Volume Four: The Dao Gives Rise to Myriad Things — Life First Sprouts

After primordial qi had grown abundant, the climate between Heaven and Earth began to show regular patterns of change. The world's temperature was no longer constant, but swung back and forth between high and low on a fixed cycle — a cycle longer than a single day and night, roughly thirty day-night cycles in length.

Through repeated observation, Pangu found that the temperature changes were linked to the path of Xiwei's movement. Across a cycle of thirty days and nights, Xiwei traced an arc through the sky. When it was closest to the Celestial Dome's center, the world was warmest; when it was farthest toward the dome's edge, the world was coldest. This cycle was the embryonic form of the four seasons.

The phase of warming he named spring; the phase where warmth reached its peak, summer; the phase of cooling, autumn; the phase where warmth sank to its lowest, winter. The four seasons — spring, summer, autumn, winter — were like four movements of a symphony, cycling endlessly between Heaven and Earth.

The changing seasons had profound effects on the world. In spring, all things revived; in summer, growth flourished; in autumn, all converged and stored away; in winter, all lay dormant, awaiting renewal. The primordial qi of the world also adjusted cyclically with the four seasons, forming a rhythmic pulse.

The four seasons first dividing — spring, summer, autumn, winter. Time was no longer merely the alternation of day and night, but also the succession of the four seasons. Time had shifted from a singular linear flow into a stream of life that carried within it cadence and rhythm.

For the first time within a single year, discernible seasonal differences appeared. Pangu found that Xiwei's arc across the sky was not fixed — it swung back and forth across the year, from south to north and north again to south. The changing angle of direct sunlight brought temperature changes, and temperature changes brought changes in wind and humidity. Spring, summer, autumn, winter — four different faces of the world now took turns across the year. Sitting upon the highest peak, Pangu fixed his unblinking gaze upon Xiwei's trajectory through the Celestial Dome. Each day, the position where Xiwei rose shifted subtly — sometimes a little to the left, sometimes a little to the right. Its path also changed — sometimes closer to the dome's center, sometimes closer to its edge. This change was so slow that it required nearly thirty days and nights to complete one full cycle, but Pangu did not lack for time.

He discovered a pattern: on the days when Xiwei was closest to the dome's center, the ground was warmest; on the days when it was farthest, the ground was coldest. When it was warm, the earth gave off a heated vapor that steamed up from the soil, carrying the scents of earth and vegetation. When it was cold, the earth contracted; everything grew taut and still. Cold and warmth alternated like a deep breathing rhythm.

When he slowly inhaled, the world's temperature swung toward warmth; when he slowly exhaled, the temperature returned toward cold. The rhythm of the world aligned so perfectly with his own. This world had been designed according to his body; every inch of its space bore his imprint.

The temperature changes brought wind. For the first time, Pangu truly noticed the existence of wind — not the air currents generated by the Wuxing cycle, but true wind driven by temperature differences. Where it was warm, air rose; where it was cold, air flowed in to fill the void — and that flowing became wind. Those winds, great and small, swift and slow, raced across the land, spiraling and clashing. Wind brought coolness and also brought moisture. It carried warmth from warm places to cold, moisture from wet places to dry. Wind was the messenger of the earth.

Pangu named the period where temperature change was most extreme the 'Great Cold.' During the Great Cold, a thin layer of frost formed on the ground — white crystals condensed from the water vapor in the air at low temperatures. He crouched and touched the frost with his finger. An icy sensation came through his fingertip, making him shiver faintly. The frost melted under his body heat and became a droplet of water. He looked at that droplet and realized that cold, too, was a kind of force — one that turned water solid and purified the air.

In contrast was the 'Great Heat.' During the Great Heat, Xiwei's light shone almost straight down upon the earth. Standing where the sunlight was fiercest, the heat of the light penetrated through his skin straight to his organs. It was not a burning heat — it was a warmth both gentle and insistent. His body absorbed heat the way the earth absorbed sunlight. That heat was not wasted — it was stored in the soil, the water, the air, and slowly released through the night, maintaining the world's warmth.

Beyond the Great Cold and Great Heat, he also identified two transitional periods. In the transition from cold to warm, temperatures rose slowly, and the world was like a body awakening. In the transition from warm to cold, temperatures fell slowly, and the world was like one sinking into sleep. He gave each of the four periods a name — spring, summer, autumn, winter. Spring was awakening; summer was blazing fullness; autumn was convergence; winter was concealment.

These four periods were not of equal length. Spring lasted seven or eight days and nights; summer, eleven or twelve; autumn, six or seven; winter, four or five. This unevenness had its inner logic — just as the mutual generation and overcoming of the Wuxing were not evenly distributed, the lengths of the four seasons, too, should be asymmetrical. Asymmetry brought change, change brought richness, and richness brought life.