Where is the rule book for life? Some would point to the Bible and maybe the top 10 rules - the 10 commandments. But the world is full of other rules - social norms, class standards, traditions, etiquette, etc. The trouble is that all these other "sub rules" are hidden - difficult to navigate and easy to miss.
Your parents, mentors, peers and others help you understand the hidden rules if you are lucky. If not - you stumble through the discovery process and in most cases it creates discord and emotional stress. And the rule book changes to complicate matters further.
Wouldn't it be nice to have just one over-riding rule! A simple rule - 5 words or less and accepted by all.
Love your neighbor as yourself.