The black and white shapes
represent opposing elements of the universe, not polar
opposites like evil and goodness but complementary ones like man and
woman. Yin (black) and yang (white) need each other to
balance and harmony.
Yin is associated with the moon, black, cold, passivity, north,
winter, and women.
Yang is associates with the sun, white, warmth, activity, south,
summer, and men.