He supposes he is a silly boy if everyone calls him so, and just a little, he wishes he could prove it wasn’t true. So he goes treasure hunting, only he can’t recognise when to take what he’s found and run. He’s been promised a horse for his troubles, so a horse he’ll work for, even though his time is usually worth much more than a horse.
He has eyes for nothing but that one little horse that will be proof against his silliness, when in actual fact that horse is really just a horse, and everything around him is trying to show him exactly what he’s looking for when he’s looking for “treasure”.
He has the eyes of a hunter rather than a scavenger, so it’s no wonder that he finds something greater than his original goal.