The Rat and the First Earthly Branch

The Rat is the first of the twelve animals of the Chinese cycle, paired with the first of the twelve earthly branches, zi. The branches are the older layer: a set of twelve cyclical signs used in China for counting days from at least the Shang oracle-bone period, combined with the ten heavenly stems to produce the sixty-term cycle by which years, months, days and double-hours are all reckoned.

The zi branch governs the double-hour around midnight, between eleven at night and one in the morning, the point at which the day turns over, and it is associated with the water phase and the direction north. The animal is read for quickness, resourcefulness, thrift and an alertness that shades into wariness. The pairing of animal to branch, not the animals themselves, is what makes the system work: the branch supplies the position in the cycle and the correspondences, and the animal is its emblem.