Upper trigram
☴
Wind · Xun
Gentle penetration.
FamilyEldest daughter
ElementWood
Hexagram 9 of 64
☴☰ Small Taming
Restraint by gentle means; small gains only.
Lower trigram
☰
Heaven · Qian
Creative force.
FamilyFather
ElementMetal
The image
Wind above, Heaven below.
Wind over Heaven: gentle penetration meeting creative force.
That combination is the whole meaning of hexagram 9. 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.