s it naturally, without force, to its proper end.8 The Yin and Yang theory became part of Taoist philosophy around 300 B.C.E. when they were mentioned in the Hsi tz''u, an appendix to the I Ching.9 Yin and Yang are defined as the two forces in nature. They are often called the two ""breaths"" or ch''i.10 Yin is the feminine principle, representing darkness, coolness, and dampness; Yang is the masculine principle, representing brightness, warmth, and dryness.11 Neither principle is good or bad; they are not opposites, but each is needed to maintain stability in the universe.12 This belief holds that everything is defined through opposition; consequently, the virtues of balance and understanding are highly valued.13 Taoism became an official religion between 100 and 200 C.E.14 Due to competition from Buddhism, Taoists adopted many Buddhist beliefs. During this pivotal point in the religion''s history, searching for self-knowledge and wisdom were replaced by searching for solutions to sorrows and other physical problems.15 Alchemy and superstition became highly popular during this period of time, as Taoists tried to escape reality rather than to control the artificial and unnatural. Many Taoists used magic and the concept of Tao to try to extend the physical life rather than to focus on the afterlife.16 Gradually the religion becomes more complicated, with a wide pantheon of gods and a ruling hierarchy.17 The leader Chang Ling took the title ""Heavenly Teacher"" in 200 C.E
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