Why do psychologists want to know everything about their clients' lives? What is the reason for this?

One of the things that psychologists do is look for patterns in people’s lives. Do they have difficulty relating to “authority figures”, for example. Psychologists look at their clients’ relationships and find out what motivates them. They want to know how the client describes himself/herself in order to know how the client thinks and reacts to other people. It’s not their lives necessarily that the psychologist wants to understand, it’s their way of thinking.