I noticed my office window was dirty with dried grimy water marks on it. I wanted to clean it but the window frames are screwed shut. And I thought, "Oh, well. If I can't clean the outside, I'll just give the inside a good scrub." To my surprise, the dirty surface was on the inside, not on the outside! This taught me a lesson: when you look at something and you see dirt, make sure it's that thing that is dirty, not your mind or your heart. How everything appears depends on what's inside of you. If your inner filter is dirty, everything you look at will seem dirty too.