When fung shui masters consult, not only do they take into account the physical changes that need to be undertaken, such as moving furniture around, but also the time in which they are to be done. Date selection is based on the philosophy that time is cyclical; positive and negative occasions occur throughout one's life at intervals that can be specified through analysing one's birth data. The Chinese use the Heavenly Stems and Earthly Branches or the five elements in yang and yin forms and the 12 animals of the zodiac to quantify time, which is then divided into four units: year, month, day and hour. To choose an auspicious time to carry out a specific activity, such as a wedding or a move to a new home, all four units of time have to be balanced and conducive to the person's year of birth and, if there is an office or residence involved, the orientation of the property. The Tong Shu or Chinese almanac contains all the information that has been collated by Chinese astronomers and astrologers and is an essential tool for date selection. In Hong Kong, it is known as the Tong Seng, as shu, which means 'book' in Putonghua, sounds like 'loss' in Cantonese. In contrast, seng means 'win' or 'victory', a far more auspicious connotation.