Ruth E. Knowlton tells this on herself: "Years ago I lived in an apartment building in a large city. The building next door was only a few feet away from mine, and I could look across the alley into the apartment on the same floor as mine. There was a woman who lived there, whom I had never met, yet I could see her as she sat by her window each afternoon, sewing or reading.
"After several months had gone by, I began to notice that her windows were dirty. Everything was indistinct through her smudged windows. I would say to myself, 'I wonder why that woman doesn't wash her windows? They look dreadful!'
"One bright morning I decided to do my spring housecleaning and thoroughly cleaned my apartment, including washing the windows on the inside.
"Late in the afternoon when I was finished, 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 windows were clean!
"Then it dawned on me. I have been criticizing her dirty windows, but all the time I was observing them through my own dirty ones!"
