A 　　Years ago, I lived in a building in a large city. The buildings next door was only a few feet away from mine. There was a woman who lived there, whom I had never met, yet I could see her seated by her window each afternoon, sewing or reading. 　　After several months had gone by, I began to notice that her window was dirty. Everything was unclear through the dirty window. I would say to myself:“I wonder why that woman doesnt wash her window. It really looks terrible.” 　　One bright morning I decided to clean my flat, including washing the window on the inside. Late in the afternoon when I finished the cleaning, I sat down by the window with a cup of coffee for a rest. What a surprise! Across the way, the woman sitting by her window was clearly visible. Her window was clean! 　　Then it dawned on me. I had been criticizing(批评) her dirty window, but all the time I was watching hers through my own dirty window. 　　That was quite an important lesson for me. How often had I looked at and criticized others through the dirty window of my heart, through my own shortcomings 　　Since then, whenever I wanted to judge(评判) someone，I asked myself first, “Am I looking at him through my own dirty window” Then I try to clean the window of my own world so that I may see the world about me more clearly. The writer couldn’t see everything clearly through the window because_____.