What is hard for people to understand? I would say mental illness. When someone has a broken bone you see a cast and know what’s going on that isn’t the case with a broken mind. A person can look and seem perfectly “normal” and then out of the blue due something erratic and out of character. This is the way of suicides and murder. The “why” question is so prevalent in these cases.
Proverbs 2:3-6New International Version
3 indeed, if you call out for insight
and cry aloud for understanding,
4 and if you look for it as for silver
and search for it as for hidden treasure,
5 then you will understand the fear of the Lord
and find the knowledge of God.
6 For the Lord gives wisdom;
from his mouth come knowledge and understanding.