Quote from : Harry Potter and the Sorcerer's Stone Book

A letter?” repeated Professor McGonagall faintly, sitting back down on the wall. “Really Dumbledore, you think you can explain all this in a letter? These people will never understand him! He’ll be famous—a legend—I wouldn’t be surprised if today was known as Harry Potter day in the future—there will be books written about Harry—every child in our world will know his name!