Upper trigram
☶
Mountain · Gen
Stillness and limit.
FamilyYoungest son
ElementEarth
Hexagram 26 of 64
☶☰ Great Taming
Power held in reserve and built up.
Lower trigram
☰
Heaven · Qian
Creative force.
FamilyFather
ElementMetal
The image
Mountain above, Heaven below.
Mountain over Heaven: stillness and limit meeting creative force.
That combination is the whole meaning of hexagram 26. Nothing about it is arbitrary — change either trigram and you get a different hexagram with a different reading, which is why the 64 form a system rather than a list.