The First Lady of Fashion returned to New York on Monday, and once again wowed New Yorkers with supportive words—and über-chic fashion. She wore a purple Isaac Mizrahi sheath and coat to the ribbon-cutting ceremony for the American Wing at the Metropolitan Museum of Art. Later that night, at the opening of the American Ballet Theatre, she donned something a little more typical: a sleeveless black Alaïa cocktail dress with a (rumored) Thakoon jacket. In both speeches, Mrs. Obama hailed the importance of art to the country’s national identity—but didn’t forget to mention fashion. "The arts are not just a nice thing to have or to do if there is free time or if one can afford it," she said. "Rather, paintings and poetry, music and fashion, design and dialogue, they all define who we are as a people and provide an account of our history for the next generation."