Ziwei Doushu bases its operation on the concept of time. So, the input of correct time of birth is essential for interpretation. Once the time of birth (year, month, date and time, i.e. the Four Pillars which contain the Eight Characters (Ba Zi)), is inputted, the life path of an individual can be formulated. From the modern scientific view, once an individual is born, the blood type is certain, while the analysis developed during the recent century on the relation between blood type and personality has possessed certain degree of accuracy. And the discovery of and research in genes further verify that many human behaviors and diseases can be predicted and categorized.

The universe, in terms of the meaning of life, is a combination of space and time. For every individual, at the instance of its birth, its life path (i.e. the length of time) is already predetermined. If born a pinewood, its life length is at least 500 years; if born a summer insect, it will never live to see the frost of winter; and if born an ephemera, it will even not see the next day’s sun. And what about the Sun? Scientists estimate its life to be 10 billion years, and it is currently 4.6 billion year old. It moves around the center of the galaxy in a 20 million year cycle (30 years ago, scientists said the stars did not move; 20 years ago, they said the Sun was at the center of the galaxy), so if there is any extraterrestrial observing at the center of the galaxy, it would say the Sun is 50 years old! What is earth people’s perception of time? It is the rise and set of the Sun, and the wax and wane of the moon. Chinese observed the Moon and formulated the lunar calendar; likewise, the ancient Babylonians observed the Sun and formulated the solar calendar. As such, the methods of astrology were ever different. However, because the alternation of the four seasons along with the changes of rain, shine, cold and hot is led by the Sun, the lunar calendar cannot fully reflect the seasonal changes in a year. Consequently, improvements were made to the lunar calendar (lunar calendar combined with solar calendar); and this is the fundamental time tool for Chinese astrology to operate with.

Looking at a man’s time of birth, the year, month, date and hour referred herein, each has its astronomic meaning:

Year: the year counting method unique to Chinese is the ‘Gan’ and ‘Zi’ (heavenly stems and earthly branches). There are 10 Gan’s and 12 Zi’s, so the least common multiple is 60, which is what Chinese refer to as a ‘Jia Zi’. The 60-year cycle is approximate to the Earth’s recession, by which the Earth move 1 degree sideward to west every 72 years; while the cycle of 12 years by the earthly branches is approximate to the revolutionary cycle of Jupiter (11.9 years). These are the feature of Chinese year counting by ‘Gan’ and ‘Zi’.

Month: The alternation of months is caused by the Earth’s revolution about the Sun. The western astrology is chiefly developed with the changes of the 12 zodiacal constellations. When in the 2nd century B.C. the Babylonians observed vernal equinoctial point (21 of March), Aries happened to be at the same position as the rising Sun. From 21 of March to 20 of April was the time when Sun orbited to Aries (or the Earth orbited to the corresponding position). But, due to the recession, Earth turns 30 degrees westward every 2,160 years; and today, the vernal equinoctial point has shifted to the Pisces, and it is about to enter the era of Aquarius. Thus, astrology shall take the astronomic errors to amend at right time.

Date: The change of date is, in terms of solar calendar, a kind of change in Earth’s revolution, and, in terms of lunar calendar, a kind of change in the Moon’s revolution. The Moon, a special celestial body, has the same cycle of revolution and spin—both are 29.5 days, such that it has one side (approx. 59% of its total surface) always facing the Earth. Scientists have long proved that the gravity of the Moon is 2.4 times more influential than that of the Sun (the effect is in proportion to mass and in inverse proportion to the square of distance). Therefore, the influence of Moon on life and characters is greater than that of the Sun. In general, astrology that bases chiefly on solar calendar tends to analyze obvious and acting personalities, while astrology that bases chiefly on lunar calendar tends to analyze invisible and psychological part of personalities, particularly the subconscious part.

Hour: The change of hours is Earth’s spin. A day is divided into 12 ‘Shi’ (24 hours). The change of minutes and seconds are in this category.