In 1892, when the statesman John Hay was building his house in Washington, D.C., he commissioned a pair of stained-glass windows from the artist John La Farge. Although he was quickly overshadowed by Tiffany, La Farge was America’s greatest innovator in the medium: the first to use opalescent glass and the first to translate flat Japanese design into windows. For the Hay House, La Farge created a peacock window and one of windblown peonies. His watercolor sketch for the peonies shown here is even lovelier than the final version.