When Norman Rockwell took on the challenge of illustrating Mark Twain's Tom Sawyer, he went to great lengths for authenticity, traveling to Twain's hometown of Hannibal, Missouri, to research characters, costumes and props.
At some point Rockwell must have felt that his original conception was too literal, too much "on the nose." His finished composition removes Tom Sawyer entirely.
Rockwell once said that "every single object shown in a picture should have its place there because it contributes to the central theme of the picture. Otherwise it simply does not belong and should be discarded ruthlessly."
Or as his hero Howard Pyle once said, "They will never shoot you for what you leave out of a picture."