YIN represents all the female qualities of creation, at least as understood by DAOists. This includes the Moon, darkness, weakness, submission, modesty, stillness, poverty and sickness.
That may sound negative, and in fact it is. YIN is the negative to YANG’s positive. But there is no true negative as both forces are equal and opposite, perfect in their differences. True fulfillment comes when you embrace both YIN and YANG in equal measure, as each complements and benefits the other.
If you strive after something without accepting its opposite, things fall out of balance. This can lead to ill health, bad luck and all manner of spiritual unhappiness. If this happens to you, your manifestation of DAO probably needs fine-tuning and your QI adjusted. Consult your nearest FENG-SHUI practitioner.
Meanwhile, back to the Gods. The Heavenly personification of YIN is XI-WANGMU.