The Eight Trigrams are arranged in one of two ways for use in Feng Shui. These arrangements are known as the Early Heaven Sequence and the Later Heaven Sequence. You can quickly identify which sequence is which by looking at the Trigram on top. In the Early Heaven arrangement, Qian is on top. In the Later Heaven arrangement, Li is on top.
As they studied the He Tu, ancient sages like Fu Xi eventually added the Trigrams to create a model of the universe known as the Ba Gua. The arrangement of the Trigrams derived from the He Tu is known as the Early Heaven Sequence. It incorporates the ideas of Yin and Yang, the Cosmic Trinity, the Eight Trigrams, and the Five Elements.
The Early Heaven Sequence shows a perfectly balanced model of reality. Yin and Yang balance each other out along each axis of the Ba Gua. From top to bottom, Qian is balanced by Kun (Heaven balances Earth). From left to right, Li is balanced by Kan (or Fire is balanced by Water). From the upper left to the lower right, Dui is balanced by Gen (Mountain is balanced by Lake). Finally, from the upper right to the lower left, Xun is balanced by Zhen (Thunder is in balance with Wind). Time has no meaning in this sequence, and there is no movement. Because of this, the Early Heaven Sequence is considered Yin due to its stillness.
According to legend, the scholar-king of the Zhou Dynasty, King Wen (who also is credited with creating the initial part of the Yi Jing) rearranged Fu Xi's Ba Gua to reflect the arrangement of the Luo Shu diagram. The Ba Gua arrangement created by King Wen eventually came to be known as the Later Heaven Sequence.
The Later Heaven Sequence shows reality as it actually exists, with Qi flowing through the seasons and moving with time. Because it shows movement, this sequence is considered Yang in nature. The Trigram on the left is Zhen, and is associated with the East. Zhen is representative of new beginnings, and with the sunrise. Li is on top, which is associated with the South. It indicates high noon, when the sun is at its peak. Dui is on the right, which is associated with West. Dui represents dusk, as the sun sets. Kan, located at the bottom, represents the North direction, and midnight. The remaining Trigrams represent transitional periods between these times.
The Later Heaven Sequence of the Eight Trigrams can be merged with the Luo Shu. Recall that the Trigram Li occupies the top of the Later Heaven Sequence and that Li is associated with the number 9. Also recall that number 9 occupies the top, center position in the Luo Shu. The Trigram Kun occupies the upper right sector of the Later Heaven Sequence and Kun is associated with number 2. Number 2 on the Luo Shu occupies the upper right corner. Working your way around, each remaining Trigram and its associated number matches exactly with the numbers on the Luo Shu. Notice that there is no Trigram for number 5, which occupies the central position on the Luo Shu.
