Yin / Yang
A starting definition: Yin / Yang : Two halves that together complete wholeness. Yin and yang are also the starting point for change. When something is whole, by definition it is unchanging and complete. So when you split something into two halves – yin / yang, it upsets the equilibrium of wholeness. This starts both halves chasing after each other as they seek a new balance with each other.
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