The metal element governs the continuum of expansion and contraction. Its organs are the lung (inspiration/expiration) and large intestine (fills/expels). It gives meaning, order, and structure to life, and thus pertains more to the left brain and autonomic nervous system functioning. Its emotion is sorrow, which takes us into loss, letting go, and the ultimate grief, death. Spiritually, it pertains to the Po - the corporeal or embodied soul which is associated with the flesh, comes into being with the first breath, and dies with the last. It is not our greatest reality, but a phantom of our true self. When we do not resist that which needs to be relinquished, we move into our deepest energetic state, that of the mysterious pass, where death ultimately results in rebirth. Something new can emerge when we let go of the old.
Many people misunderstand this element. I know I did. I used to think that life was expansion and death was contraction. My present understanding is that it is actually the opposite. After working with fertility for so many years, the subtle energy of embodiment was felt as a contraction of new energy in the depths of a woman's body. Years ago, I started working with Hospice, and noticed that when somebody was leaving this embodiment, there was a great expansion of energy as the spirit was no longer held by the limitation of the physical body.
While this may not be an awe inspiring realization, it has some elements that many of us overlook. According to the Tao, all of life's expressions operate via opposing forces. Openness or expansion begets the ability to hold. Being closed or contracted requires relinquishment, so emergence can take place. In other words, death begets life.
Spirit becomes trapped by the Po as it experiences this existence. At retreat we focus on breath work and letting go exercises to open up to this energetic. We expand so contraction can occur. We let go, so something can take hold.
In the words of the Tao te Ching: Those who try to control... Go against the direction of the Tao If you want fullness, empty yourself. If you want birth, let yourself die. If you want everything, give everything up.