The Universal Post or Yin Yang Standing Posture introduces the idea of movement into your standing practice. By shifting the weight onto one leg and letting the other leg hang empty in space, you are training the body how it will feel to move without moving. This idea of stillness and motion coexisting relates to the Yin and Yang theory. The Universal Post lets you practice this coexistence without moving. Later, you will practice this coexistence while moving.
Remember, the concept of Yin and Yang is as ancient as Chinese philosophy. The origin story said there was a primordial chaos (Wuji) out of which an egg was born. When the egg split, the heavy yolk sank to become the Earth (Yin), while the light egg white rose to become the Heavens (Yang).
Two lines represent Yin and Yang. Yang is a solid line that represents brightness, lightness, masculinity, and the tendency to move upwards. Yin is a broken line that represents darkness, heaviness, femininity, and the tendency to move downwards.