What does the lunar sun mean?

"Tao is tai chi. Taiji gives birth to two instruments, which are divided into four images and four images are divided into eight diagrams. "

The lunar sun belongs to the second of the four elephants (the four elephants are divided into lunar, shaoyin, sun and shaoyang). The two devices are the basic units of gossip, one is Yin, the other is Yang, the other is Sun, and the other is Taiyin.

The sun is clear and the moon is soft.

I am an amateur Zhouyi lover, and the statement may not be too popular. If I don't understand,

For more details, please refer to relevant information.