A mystical concept derived from Taoism that is extremely relevant in a study of the workings of human Consciousness is the idea of the Tao, a balance of polar energies inherent in all Nature. Taoist tradition teaches that if we are able to strike a balance between these polar forces, and harmonize these two competing polarities within ourselves, justice and order will result within and around us. 
Falling prey to a perpetual imbalance of these energies would result in the experience of suffering and chaotic conditions. This makes perfect sense when we understand the properties of these polar energies.
To do this, let's begin by analyzing the basic symbolism of the Tao symbol. It is comprised of a circle, inside of which are two inter-locking swirls, one light and one dark. Inside each swirl is a smaller dot which is the opposite color of the swirl itself The circle represents all of Creation. A circle is never-ending. It has no beginning or end. It is a perfect shape, as it has no corners, rough edges, angle, or irregularities. Thus it represents God, or Creation itself, the All-That-Is.
The two swirls represent change, of which all Creation is comprised. All that exists is in a constant state of change. All matter passes from form to form in an endless dance of Creation. Life itself is change. Inability to change is the equivalent of death and non-existence. Therefore the two swirls inside the circle represent this ever-changing dance of matter taking place within the whole of Creation. The two dots within each swirl represents the idea that, no matter how deeply into one polarity or the other we may travel, the seed of the opposite energy is always carried within each polarity.
Let's now examine the expressions of the polar energies that comprise the Tao. The light area is called Yang. It represents the following general qualities: Light, Solar, Day, Masculine, Active, Analytical, Dominant, Aggressive, Left-Brain, Right-Body. The dark area is Yin, which represents the expression of the following qualities: Dark, Lunar, Night, Feminine, Passive, Intuitive, Submissive,Right-Brain, Left-Body.
A human being's Consciousness is comprised of all of these energies, as is the Cosmos. This is why it may be said that we are created in the image and likeness of God. Neither of these sets of opposing energies should be seen as being all good or all bad. Our Consciousness contains all of them. A balanced and fully-functional Consciousness will contain all of these qualities in balanced proportions. This balance is the essence of the key to mental and physical health, and the ability to think critically and make decisions that will result in prosperity for the individual and society as a whole. When these energies are thrown out of balance, and one begins to severely dominate the other, suffering and chaos are the result.
One of the oldest symbol sets in human antiquity contains many parallels to the concept of the Tao. Known as the Blade and the Chalice, these two symbols also represent the competing masculine and feminine polar energies. The Blade was depicted as a upward-pointing triangle. This served as a rudimentary phallic symbol, representing the solar, masculine, Yang energy. The Chalice was a downward-pointing triangle which represents the feminine womb, calling to mind the qualities of the lunar, feminine, Yin energy.
When these energies are combined in a balanced proportion, a third symbol was used to represent their harmonization. It is the Blade and the Chalice interlocked in the form of a six-pointed star. This symbol later became known as the Seal of Solomon in Judaic, Islamic, Christian and Alchemical mystic traditions. The seal represents the combining and harmonizing of the sacred masculine, or Solar energies with the sacred feminine, Lunar energies (hence the term "Solomon" - Sun and Moon), to create the"blazing star" of awakened Consciousness. It is only possible for us to exist in balance with our natural environment (which is made of these energies) when these two divine energies are working in unison within ourselves.
This concept of balancing the energies within our Consciousness, so that we harmonize ourselves with the divine proportions of these energies found in Nature, is called the Hermetic Principle. Named after the Greek god Hermes, the Messenger of the Gods, this idea has also been expressed by the adage "As Above, So Below; As Within, So Without." This conveys that that which takes place within our consciousness is reflected without to our perceptual surroundings. If our consciousness exists in balance and harmony, our external conditions will reflect this internal harmony and order. consciousness thrown out of balance will create chaos and disorder in our external reality.
One can appreciate the simplicity and beauty through which our ancestors depicted these concepts through symbolism. In undertaking the study of this symbolism itself, we begin the task of uniting these opposing polarities within ourselves. Grasping the true meaning of these symbols assists us in this task - a task which is one and the same as our journey of spiritual development and Evolution in Consciousness.