Nicholas Penny, senior curator of sculpture and decorative arts. The work of fifteenth-century sculptor Desiderio da Settignano inspired contemporaries to declare that he "brought cold marble to life." On the occasion of the exhibition Desiderio da Settignano: Sculptor of Renaissance Florence, Alan Shestack, deputy director of the National Gallery of Art, talks with senior curator Nicholas Penny about Desiderio-the sculptor and the exhibition.