Yin and Yang.

The universal life force Qi is believed to be composed of yin and yang; a system of opposites that must always be in balance.

These are opposite, but complementary, forces.

Yin represents everything about the world that is dark, hidden, passive, receptive, yielding, cool, soft, and feminine. Yang represents everything about the world that is illuminated, evident, active, aggressive, controlling, hot, hard, and masculine.

All things can be identified with yin and yang, and keeping the yin-yang ratio in balance is necessary to prevent illness in a body or maintain peace and harmony in buildings.

Naturally, the masculine Yin has to be present in a greater quantity than the feminine Yang for perfectly-balanced harmony to be achieved. Masculine superiority is written into the life-force of the universe it seems. At least it is according to the men who most likely thought of the idea.