Letter from the editor.

• Position: Editorial

In our cover story, we look at the power of images, and how they're used to sell not only products but ideas. We've chosen 14 posters from a recent book, covering a wide range of topics. They may make you smile, or make you angry, but that's the point: They get you to think, and we hope they'll be the basis for lively class discussions.

Inside, two Times Op-Ed columnists weigh in with their takes on some of the issues surrounding Wal-Mart and its impact on America. In our...