They are two of the most beloved artists of all time: Edgar Degas, celebrated for his extraordinary draftsmanship and tender, dynamic paintings of ballerinas; and Vincent van Gogh, adored not just for his tragic life story, but for his shimmering canvases, those world-famous images of starry nights and bright sunflowers. Now, a museum dedicated to Van Gogh's oeuvre is asking whether it is "appropriate," in anno 2020, to exhibit a drawing by Degas. To be sure, it's not just any drawing. The sketch in question depicts a bathing woman from behind, her derriere revealed in all its flesh and glory....