Truth or Wives tale?
Ask your grandmother how she cleaned her windows in the old days and she will most likely tell you that they would use newspaper. More precisely waded and scrunched up newspaper used to polish the windows. Like it was the newspaper that magically did the work.
Push her a bit further and what she will tell you will depend where in the world she came from. Some will tell you to put several table spoons of lemon juice in half a bucket of water, while others will tell you to use equal parts of vinegar and water, and still others will use both lemon juice and vinegar in water.
Then the process seems to be to use a cloth or some of the waded up news paper to apply which ever mix to the glass and then several more wads of newspaper to rub the glass dry. There you have it the entire process.