"Live as if the world were what it should be to show it what it can be."
Okay, so the quote is from Angel. Don't judge.
Also, the wording is a little awkward. But that's because it's tough to jam big concepts into bumper-sticker sized nuggets.
We don't live in the world we should live in. We don't live in a world where people do all the things they should do and never do the things they shouldn't. It would be great if we lived in the world of shoulds, but we don't. Not collectively, anyway.
There are those of us who do live in the world of ideals. There are people (you may have met one or two in your life) who always do the right thing. They are righteous without being self-righteous, understanding without being condescending, superior without being conceited. They seem genuinely confused by the presence of evil in the world. They may understand evil as a concept, and may realize that it is possible for supernatural influences or large groups (nations, corporations, political parties, etc) to commit evil acts, but evil on an individual level is inconceivable. Why would a person do things that they shouldn't?
Here's the thing: we should all be a little bit more like that person. We should all be better than we are, and we should all expect the best from one another.
But one of the most important things i have learned in my life so far is that, while you should always expect the best, you also need to be prepared for the worst. You should expect people to treat you fairly and to behave with honor and respect, but you should prepare to get screwed by everyone you meet.
You don't have to live in reality if you don't want to. You can live in the world of shoulds. But most sane people live in reality, so if you ever want to have anything to do with another person, you need to at least be able to navigate through reality.
There is only one person whose behavior you can control, and that's you. It doesn't matter how other people behave. You should still do the things you should. The best you can hope for is that your behavior will inspire (or shame) others into behaving as they should. Prepare to get screwed, but expect that you won't be. Live as if the world were what it should be to show it what it can be.