Three of the energies/phases or different varieties of "Qi" discussed in the Wuxing overview are further divided. Earth is composed of "Mother" and "Mountain". Metal becomes "Lake or Marsh" and "Heaven". Wood becomes "Thunder" and "Wind". Each "Qi" has its own trigram associated with it and the eight combined trigrams, their sequencing, and their interactions are known as a Bagua.
The Chinese term Xian Tian roughly translates to "Before Heaven". This sequence denotes a world in perfect balance. The phases in this sequence are in stasis (motionless) with no movement, interaction, or transformation.
The trigram Qian (Metal/Heaven) is on top in the South with Kun (Mother/Earth) below in the North. Li (Fire) and Kan (Water) are on the left and right forming a pair. Zhen (Wood/Thunder) and Xun (Wood/Wind) communicate with one another forming a diagonal pair. Gen (Earth/Mountain) and Dui (Metal/Marsh or Lake) also form a diagonal pair. Each of these pairs are opposite seeking balance and harmony and making the arrangement of the trigram pairs fully symetrical.