Upper trigram
☷
Earth · Kun
Receptive yielding.
FamilyMother
ElementEarth
Hexagram 24 of 64
☷☳ Return
The turning point; light comes back.
Lower trigram
☳
Thunder · Zhen
Arousal and shock.
FamilyEldest son
ElementWood
The image
Earth above, Thunder below.
Earth over Thunder: receptive yielding meeting arousal and shock.
That combination is the whole meaning of hexagram 24. 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.