The terms Zi (子), Chou (丑), Yin (寅), Mao (卯), Chen (辰) and so on refer to the Earthly Branches (地支), which are part of the traditional Chinese timekeeping system. This system divides the day into 12 double-hours, each lasting approximately two modern hours. Each of these time segments is named after one of the 12 Earthly Branches.
The Earthly Branches (地支, Dìzhī) are a traditional Chinese system used to divide the day into twelve two-hour segments, each associated with a specific character and time. These branches form the basis of the ancient timekeeping system, the zodiac cycle, and even agricultural and spiritual practices.
The cycle begins with 子 (Zi) — Rat — 11 PM to 1 AM
Zi is the first Earthly Branch and symbolizes beginnings, like the seed of life germinating in darkness. Midnight is when the Yin energy reaches its peak and begins to give way to Yang. The rat, active at night and associated with fertility, represents the idea of life stirring in the void.
丑 (Chou) — Ox — 1 AM to 3 AM
This time is still dark, but Yang energy is gradually rising. The ox was traditionally used to plow the fields at dawn, so its image became linked to the slow, steady pre-dawn labor. The ox embodies patience and quiet strength in the stillness before sunrise.
寅 (Yin) — Tiger — 3 AM to 5 AM
The Yin hour is when the darkness starts to lift, and predators like the tiger are believed to be most active. The tiger represents ferocity, movement, and awakening, mirroring the increasing Yang energy just before sunrise. It is a time of subtle stirring and alertness in nature.
卯 (Mao) — Rabbit — 5 AM to 7 AM
This is the time of dawn, when the sun begins to rise, and the world is bathed in soft, silvery light. The rabbit, a quiet and cautious animal, is often seen at this time nibbling in the fields. It symbolizes gentleness, new beginnings, and the start of visible life in the day.
辰 (Chen) — Dragon — 7 AM to 9 AM
The dragon is a mythical creature, not observed in the wild, but it represents majesty, strength, and the power of transformation. This period reflects the full awakening of the world, when people begin their work and the energy of the day becomes vibrant and forceful, just like the image of a soaring dragon.
巳 (Si) — Snake — 9 AM to 11 AM
By now, the day is in full motion. The snake, often seen basking in the morning sun, is linked to this time. It's alert, calm, and sensitive to temperature—symbolizing awareness, warmth, and focused movement. Si hour represents mature Yang energy, steady and quietly active.
午 (Wu) — Horse — 11 AM to 1 PM
Wu is the only branch that directly means noon in modern Chinese. It represents the peak of Yang, when the sun is highest, and people often feel the most energetic. The horse, swift and free-spirited, matches this vigorous time. It was also commonly ridden or used in work during daylight hours.
未 (Wei) — Goat — 1 PM to 3 PM
After the midday peak, energy begins to slow. The goat, a calm and pastoral animal, is often associated with grazing in the afternoon sun. This is a time of mildness and digestion, both literally and energetically. It's the shift from Yang to Yin, gentle and reflective.
申 (Shen) — Monkey — 3 PM to 5 PM
This is a lively time of day. Children play, laborers finish tasks, and the heat starts to subside. The monkey, clever and energetic, reflects this agile, playful energy. Shen hour is associated with flexibility, quick action, and sociability as the day winds down.
酉 (You) — Rooster — 5 PM to 7 PM
You hour is the beginning of evening, a time to return home and prepare for nightfall. The rooster, which crows at dawn but also roosts in the evening, represents closure, routine, and reflection. This period is associated with restoring order and transitioning back to Yin.
戌 (Xu) — Dog — 7 PM to 9 PM
This is when households quiet down, and people guard their homes, which is why the dog—a loyal and alert animal—fits this time. Xu hour is associated with protection, loyalty, and watchfulness in the early night, when safety and stability become a focus.
亥 (Hai) — Pig — 9 PM to 11 PM
Hai hour marks the end of the day, when most people sleep. The pig, a symbol of rest, abundance, and peace, fits this time perfectly. It represents the return to stillness and the preparation for renewal as the cycle gets ready to begin again at Zi hour.
These twelve branches form the basis for many traditional Chinese systems, including the zodiac and the sexagenary cycle. They also served as a precise timekeeping method in pre-modern China, especially before mechanical clocks were widely available.