The calendar in Vietnam’s ancient agricultural society was based on the regularly changing phases of the moon. Most Vietnamese, even city dwellers and overseas Vietnamese, have a lunar calendar in their homes to consult for the dates of festivals and auspicious days.
The date of the New Year varies from year to year because it is based on the lunar calendar. The equinoxes and solstices that mark the beginning of the European seasons are taken as the midpoint by the Asian calendar, with the result that each Vietnamese season begins six weeks earlier than its European counterpart.
Each year is “sponsored” sequentially by one of twelve animals of the Vietnamese zodiac: the Rat comes first, and then the Ox or Buffalo, followed in order by the Tiger, Cat or Rat, Dragon, Snake, Horse, Goat or Ram, Monkey, Cock, Dog, and last of all, the Pig.
Of these animals, one is mythical (the dragon), and four (rat, tiger, snake, and monkey) are wild, shunning contact with humans. Seven are domesticated. Every twelve years, the sponsorship reverts to the same animal. For example, the years 1976, 1988, 2000, and 2012 are Dragon Years.
In addition, the Vietnamese use another set of ten heavenly or celestial signs, usually called “stems.” Combining the ten heavenly stems with the twelve earthly animals results in a sixty-year cycle, similar to the Western century of one hundred years. The celestial “stem” attached to the zodiac animal provides a modifying influence on the characteristics of the animal. For example, the year of the dog sign can be “modified” by five of the ten different associated “stems.”
Each year has import for humans who have converging or diverging signs. The following examples are given in the order that they occur in the cycle. Each of the twelve animals also “sponsors” a two-hour period of time of the day.