Here's a story my dad told me a long time ago when I was a kid :
It had been a grueling day, the rally was a success, and everyone was exhausted. The local crowd that Mohandas Gandhi was addressing all day was slowly dispersing. All except for the reporters and photographers who were still following him and his disciples around asking questions. The man was starting to get a little annoyed. It was then when Gandhi half-jokingly uttered those words to documentary photographer, Margaret Bourke-White, who was also a close friend of his. Of course later on he would often repeat the line during press interviews, but this was supposedly how the quote came about.