I've recently read the following quote from Rumi:
All evil qualities—oppression, hatred, envy, greed, mercilessness, pride—when they are within yourself, they bring no pain. When you see them in another, then you shy away and feel the pain. We feel no disgust at our own scab and abscess. We will dip our infected hand into our food and lick our fingers without turning in the least bit squeamish. But if we see a tiny abscess or half a scratch on another's hand, we shy away from that person's food and have no stomach for it whatsoever. Evil qualities are just like scabs and abscesses; when they are within us they cause no pain, but when we see them even to a small degree in another, then we feel pain and disgust. [Source: The Discourses of Rumi]
I don't like the word "evil", but Rumi uses this word with much discernment in the rest of the book, so I do not consider it a problem in this context. This passage really makes a lot of things clear to me, such as the hatred involved in many fundamentalist religions (they see in others what they can barely control in themselves) or the fact that most people (including myself) are constantly upset about the same things. Sometimes I wonder what was there first: My being upset or the thing I'm upset about. This quote also reminds me of a part of the New Testament:
Why do you see the speck in your neighbor's eye, but do not notice the log in your own eye? Or how can you say to your neighbor, 'Friend, let me take out the speck in your eye,' when you yourself do not see the log in your own eye? You hypocrite, first take the log out of your own eye, and then you will see clearly to take the speck out of your neighbor's eye. [Luke 6:41-42]
I like how these psychological insights can be found in many religious texts.