THROUGH everything in life flows the lazy line of yin and yang, first looping this way, then leaning that way, forever alternating the two energies, male and female, active and receptive, extrovert and introvert, warm and cool. The picture wobbles and wavers and bends and bows and swings and sways, but always, in the end, the two tides are kept in balance and the circle is maintained. The yin cannot pull away from the yang; the one cannot exist without the other.