In Chinese philosophy, time is cyclical. For instance, the signs of the zodiac repeat themselves every 12 years. From a fung shui perspective, there are different influences and energies in different hours, days, month and years. Widely practised in Hong Kong, the Flying Stars school is a traditional branch of fung shui that takes time into account. Essentially, time is divided into nine units - or periods - of 20 years each, giving a total of 180 years. It is believed energy completes a full cycle every 180 years, which is known in Putonghua as a da yun, or in Cantonese as a dai wan, a 'large period'. The term yun in this context has been translated into English as luck cycle, fortune or age, creating much confusion for the casual reader. This system of measuring time has been used for almost 5,000 years; we are now in period eight of the 27th large period. Periods are used in Flying Stars calculations to assess the energy of a property. Period eight started on February 4, 2004, and will run until February 4, 2024. Period seven ran from February 4, 1984, to February 4, 2004. Thus, two properties with the same orientation, for example, one completed in 1996 (period seven) and the other last year (period eight) can exert different effects on their occupants.