The eight Trigrams, the base of the I Ching system of divination, were created by observing a tortoise shell and symbolize the eight main forces of the Universe. Combined in 64 hexagrams, they represent the consequences of the interaction of these forces with one another.
This is what they mean:
LI - Trigram of Fire
This represents the light which makes everything shine. It signifies dedication and passion. It's the symbol of glory, fame and denotes excellent capacity. It represents the war, the Army and impetuous currents. The organ which corresponds to the eye.
"Li" is the middle daughter between Heaven and Earth.
KUN - Trigram of the Earth
This represents the start and abandonment. It is receptive and protective. It symbolizes the vase, the earth ready to be fertilized by the Sky. The organ corresponds to the stomach.
"K'un" is the mother of the other trigrams
TUI - Trigram of the Lake.
It is associated with pleasure and the consequence of the desire to reproduce itself. Tui, "lake", is linked to the west and autumn and can signify also decline and separation. The organ corresponds to the mouth.
"Tui" is the youngest daughter of Heaven and Earth.
CHIEN - Trigram of Heaven
It is the principle of superiority. It is the Creator. The organ corresponds to the head and symbolizes the Head, he who governs.
"Ch'ien" is the father of the other trigrams.
KAN - Trigram of Water
Water bathes and therefore nourishes but can also cause rotting. Its symbols are the well and the ditch. It signifies an activity which has ceased and the danger of stagnation. Its organ is the ear. "K'an" is the son of Heaven and Earth.
KEN - KEN - Trigram of the Mountain
This is the symbol of immobility, linked to sitting down and meditation. It means interruption or protection against the danger of invasion against obstacles which prevent our progress. Its organ is the hand. "Ken" is the youngest son of Heaven and Earth.
CHEN - Trigram of Thunder
It's the symbol of growth and movement. Its emblem is lightning. It represents the vital form which awakens and excites. Its energy finds expression both in Love and in work. Its organ is the foot. "Chen" is the eldest son of Heaven and Earth.
SUN - Trigram of the Wind.
This is the gentle force which penetrates everywhere, but which can also be caused by desperation. Sometimes it is inconstant and can disperse its own energy. Its organ is the thigh.
"Sun" is the daughter of Heaven and Earth.