What does virtue mean in the solar calendar?

Are you asking Tiangen? Eight diagrams: Gan, Kun, Xun, Dui, Gen, Zhen, Li, Kan and Gen are one of the eight diagrams.

The eight diagrams algebra is seven, and the eight diagrams are located in the northwest. Eight diagrams belong to the root soil, Kun and Gen (soil) are born in the eight diagrams, and Kun and Gen (soil) are born in the trunk. Eight diagrams flourish in four seasons and decline in autumn, which are the five elements corresponding to eight diagrams.

Roots are the ground and roots are the mountains. Eight diagrams are divided into yin and yang, Kan, Gen, Zhen and four hexagrams, among which the root is boy.