Each month is divided into ten-day periods, six of those in turn considered a special time period, and six of those equaling a full year. In addition, each year is divided into twenty-four climatic periods called breaths or nodes, described by such phrases as “full of snow” or “clear and bright.” Every year, month, day, and hour are further identified by a combination of ten heavenly “stems” and twelve earthly “branches” (the monthly or zodiacal symbols). The ten heavenly stems are associated with colors, two stems with each of the five symbolic colors (azure, red, yellow, white, black), which are in turn linked to the four directions and center as well as to the five elements. Branches and stems are both primarily numerical designators, but each also bears important symbolic connotations. If you match one stem with one branch for succeeding years (S1/B1, S2/B2 … S1/B11, S2/B12, S3/B1, and so on), you end up back at the beginning after sixty years. In this system, only odd-numbered stems combine with odd-numbered branches, even-numbered stems with even-numbered branches. We are currently in the sixty-year cycle that began in 1984.

The result of all this calculation is an extremely detailed system of pinpointing ritual times according to a host of definitive characteristics. Each event occurring on earth has its heavenly parallel. For every conceivable type of human behavior there is an auspicious moment. The calendar has thus been not merely a way of keeping track of times for religious observances, but a kind of temporal map for negotiating the cosmos as well. Each year, during the ninth lunar month, imperial officials set up the liturgical calendar for the year to come.