The greatest American painter of the outdoor scene, Winslow Homer, was also probably America's most important artist of the last century. He was one of the first artists to go outdoors to paint rather than work in a studio. Although he also used oils, he was a pioneer in making watercolor—at the time generally considered a fit medium only for milady's parlor or the schoolroom—not only respectable but widely admired. Now Homer is being honored by the biggest retrospective exhibition of his works ever held. On view at Washington's National Gallery from November 23 to January 4 and at New York's Metropolitan Museum from January 29 to March 8 will be 242 of his pictures. The sampling of his work presented below suggests the variety of the show.