Karadi Tales Picturebooks and Edelweiss let me read this book for review (thank you). It will be published September 1st. The illustrations are lovely.
First, his horse takes off and he can't go after it. When it returns, it brings him more horses. His son loves the horses but fell off and broke his leg. Everyone is sorry for him but the father still says it could be a good thing.
Then, while his son is recuperating. another kingdom declares war. All the young men have to fight but his son can't.
Before long, the villagers change their perspectives and start looking for the good, not just the bad.