The most devastating attack on Mitt Romney at Tuesday’s Democratic Convention came from Michelle Obama, who did not mention Romney’s name and said not a single cross thing about him. She devastated him by implication. If Romney was the son of privilege, she and her husband were anything but. What she said directly is that Barack Obama understands people who are struggling. What she didn’t have to say is Mitt Romney doesn’t. As a general matter, her speech was a big hit: good enough that even Fox News was kind to her. But the specific stories — about her father working through the pain of multiple sclerosis, about the debts she and her husband accumulated from college — served a powerful campaign purpose. A speech that was thoroughly apolitical on the surface carried multiple political messages, linking a very traditional message about parenting with a call for social justice…. Oh yes, and she also said that for husband, “success isn’t about how much money you make, it’s about the difference you make in people’s lives.” Did any other presidential candidate come to mind as perhaps having a contrasting approach? Michelle Obama was much too polite to say. She didn’t have to.