Yin and yang
Yin and yang are the two opposing but complementary energies, forces or principles in Chinese philosophy whose interactions cause the universe to come into being. The interplay of yang and yin forces governs all formation, movement and change.
The yang force in the universe has characteristics that are masculine, active, bright, positive, hot and contracting.
The yin force in the universe has characteristics that are feminine, passive, dark, negative, cold and expansive.
Traditional Chinese medicine teaches that perfect harmony between the yang and yin elements in the body brings health. Conversely, the undue preponderance of one or the other results in disease and death.
For the application of yin and yang to diet, see Macrobiotics.
Elizabeth Clare Prophet, The Astrology of the Four Horsemen.