Tao, the undivided, Great One, gives rise to two opposite reality principles, Darkness and Light, yin and yang.

These are at first thought of only as forces of nature apart from man.

Later, the sexual polarities and others as well, are derived from them.

From yin comes Kun, the receptive feminine principle; from yang comes Chien, the creative masculine principle ; from yin comes Ming, life; from yang, Hsing or essence.

Each individual contains a central monad which, at the moment of conception, splits into life and essence, Ming and Hsing.
These two are super-individual principles, and so can be related to Eros and Logos.

In the personal bodily existence of the individual they are represented by two other polarities, a p’o soul (or Anima) and a hun soul (or Animus).

All during the life of the individual these two are in conflict, each striving for mastery.

At death they separate and go different ways.

The anima sinks to earth as Kuei, a ghost-being.

The animus rises and becomes Shen, a revealing spirit or god. Shin may in time return to Tao.

If the life-forces flow downward, that is, without let or hindrance into the outer world, the anima is victorious over the animus; no “spirit body” or “Golden Flower” is developed, and, at death, the ego is lost.

If the life-forces are led through the “backward-flowing” process, that is, conserved, and made to “rise” instead of allowed to dissipate, the animus has been victorious, and the ego persists after death. It is then possessed of shin, the revealing spirit.

A man who holds to the way of conservation all through life may reach the stage of the “Golden Flower” which then frees the ego from the conflict of the opposites, and it again becomes part of Tao, the undivided, Great One. ~Richard Wilhelm, The Secret of the Golden Flower.