I've seen the quotation many times in different forms: We don't see things as they are; we see them as we are. In other words, our perception of what we see is strongly influenced by what we are as people and what's going on in our lives. The same action by the same person can be seen in various ways by different people who are leading different lives. If I pick up a piece of trash on the street, one person may see me as a civic-minded citizen, while another will see me as a do-gooder who's just trying to impress other people. Someone else may see me as an insecure person who's trying to make other people like me, while a fourth person may see me as a clean freak, a person who's so obsessed with cleanliness that I even have to clean the streets.
What does this mean to me? Quite simply, it warns me that I need to be very slow to judge others. If I have an argument with my wife this morning, I may have a problem later in the day when someone does something that I don't like. I may judge that person or his or her actions based upon what I'm feeling about the argument. This is why I really appreciate the concept of being an observer, and not a judge. When I see someone do something that I don't like, I can remind myself that there may be many different reasons for which that person has done that something. Once I remind myself of that fact, I can also withhold judgment, realizing that I really don't know which of the reasons is correct.
Of course, some actions are just stupid and obnoxious. A person throwing a bag of trash out of a car window as they drive by is doing something horrible, and a person stealing money is also doing wrong. The filters caused by where I am in life aren't giving me a wrong message in these cases. But they are still unique messages. A different person will see those two things in a different way.
I suppose that my reason for pondering this idea is that I want the way that I am to be positive and compassionate. I want the way that I see the world to be fair and as impartial as I can imagine. I don't want to leap to harsh judgment just because of something in my own life--if I do that, I'm affecting myself just as much--and probably more--than I'm affecting the other person. And I don't want to do that.
And on another hand, I also want appreciation of beauty to be a part of who I am so that when I see sunsets and rainbows, I can recognize their beauty and feel awed and inspired by it. Some people do little more than glance at miraculous sunsets, for they don't see the beauty in them--for they don't see the beauty in themselves.