Kathleen J. Wu writes, "As a fan of Sheryl Sandberg, I agree with the "lean in" mantra, and I want women to be more confident, sit at the table and speak up. I'm not going to disagree with any of that. But I worry that the young women we're trying to imbue with all this moxie believe that they can somehow synthesize it. They can't. Before there can be confidence there must be expertise, knowledge and mastery. It's just like figure skating. A great costume can enhance a brilliant skater, and a lousy outfit can undercut how a great skater is perceived. But the best costume in the world won't make up for a stumbling performance."