How to understand the person

There are many ways people have said to understand a person. There must be a thousands of ways to understand a person and his traits... Here is something written by AMISH which I found very relevant for any situation, very simplistic approach but I feel very effective
"If you want to understand a persons character, look closely at there interpersonal behaviour and transactions" 

"It is attachments that make a person blind. It makes people forget their moral and even make them forget themselves, what they are and what they are capable of " 

If you believe in hindu philosophy then to add to this, it is one's attachment which keeps the soul looping through the cycles of birth and death until his all attachments are untangled and burnt ...