In conversation with Susan Larsen, of the Smithsonian’s Archives of American Art, the American artist Richard Diebenkorn recalled the first time he saw the work of Paul Cézanne. It was “very disquieting,” he said, “shocking.” His description of the Impressionist’s work—“the crazy sort of … spareness,” and the “tabletops where I felt apples should roll off,” and the “buildings with skewed verticals and horizontals”—is an apt description of Diebenkorn’s own earliest work, rarely seen and now on view here. Start with the thumbnails for an up-close and isolated view of these heady experiments with line and composition. —C.J.F.