People see their own nature in others, whether present or not
Okay, this may not be a very original idea. I am paraphrasing a concept that has been said many times before and probably far more eloquently. In psychobabble they call this "projection". Nevertheless, I see the fundamental truth of this idea more clearly with each passing year.
All of us have had the experience of either totally misjudging someone or being totally misjudged by someone else. I know in my life I have struggled with one relationship or another involving friends, family and co-workers. It seems clear to me that many of these conflicts occur when the players are just not equipped, either emotionally, as a matter of individual character, to understand the other. I have been most frustrated in my attempts to work productively with people who have a history of behaving badly. These people invariably justify their bad behavior as a reaction to being mistreated themselves. Turn around is fair play, eh? The bottom line is that they know they are capable of, and willing to, under the right circumstances, behave unscrupulously or with malice. They can't believe others wouldn't do the same.
How do you feel when someone shares a bit of nasty gossip with you or talks badly about someone you mutually know? You're probably thinking, "I wonder what they say about me when I'm not around?" They betray their nature by assuming you are a kindred spirit. From their perspective, everyone behaves this way. They can't image otherwise.
One interesting notion is that in your dreams, every person, place, or thing, is really just a aspect of yourself. After all, you are imaging that dream world, so every aspect of it has to come from you. In the waking state, I think we are still confined by the notion that everything and everyone is a variation, and extension of ourselves. Our inability to accept the reality of those with fundamentally different natures even extends to different species. We attribute human characteristics to our pets and treat them as furry, four-legged family members.
People with character traits we admire; honesty, compassion, perseverance, see those traits in others because they have no personal basis for understanding differently. They tend to have a rosy view of the world and believe people are basically good...like themselves.
People who regularly practice dishonesty, self-pity, malice, and other undesirable traits, see everyone else as kindred spirits. They are eager to share a bit of nasty gossip with you. Surely those who have done better than themselves have had unfair advantages or perhaps they were just more successful in their conniving. Lucky bastards! People with this perspective are hard to get along with because they inevitably assume you are going to try and screw them. That is the way of their world.
The thing I am trying to get at is this:
People often think they understand each other better than they actually do. If you are struggling with a relationship and you find yourself asking, where did that come from?! You are probably dealing with someone who has a fundamentally different view of the world and their place in it than you do. This insight can help you manage that relationship better...but be careful. If you are dealing with someone who expects to be mistreated, they will inevitably find a way to see that coming from you no matter how you behave.