The Dao that can be told Is not the eternal Dao. The name that can be named Is not the eternal name.
The unnamable is the eternally real.
Naming is the origin
of all particular things.
Free from desire, you realize the mystery.
Caught in desire, you see only the
manifestations.
Yet mystery and manifestations
arise from the same source.
This source is called darkness.
Darkness within darkness.
The gateway to all understanding.
Lao Tse begins his Dao De Jing with these stanzas. The meaning is both simple and complex. The first two say we can experience perfection, even know it, but not describe or teach it. (It is always so with mystical quantities and qualities. It's what makes them mysterious and, therefore, mystical.)
Recognising the relevance of the Yin & Yang symbol to these stanzas is a little more subtle. The simplest interpretation is the familiar saying "you cannot have light without darkness." A Daoist might say that darkness and lightness create each other. That is the balance visually described with the Daoist symbol of yin and yang.
