In 2010, thirty-one paintings by Pierre-Auguste Renoir traveled from the Clark Art Institute, in Williamstown, Massachusetts, to Madrid’s Museo Nacional del Prado. In part because French Impressionism is not conspicuously well represented in Spanish museums, “Pasión por Renoir” was immensely popular and heavily attended, earning the Clark a great deal of good will. The result of this act of museum diplomacy can be seen in the Berkshires through October 10: “Splendor, Myth, and Vision: Nudes from the Prado,” an extraordinary gathering of twenty-eight sixteenth- and seventeenth-century Old Master paintings from the legendary Spanish collection, twenty-four of which have never before been seen in the United States, embracing mythological, historical, and religious subjects, from both the Old and the New Testament, along with allegorical emblems of the senses, and more.