On April 9, 1973, Carla Pellegrini opened a new Milan gallery space with “Sickle and Hammer,” a solo show by the Italian designer Enzo Mari, who died last October. It was Giuliana Einaudi, a student, who first suggested that the symbol’s sophisticated graphic quality, as well as its historical and emotional impact, could be a good springboard for Mari. He set to work, depicting its unmistakable lines in various media. Almost 50 years later, and with the help of Mari’s archives, the gallery has recreated the show. How has the significance of the sickle and hammer, its intonation of threat, shifted over time? Sculpture, installation, photographs, and a documentary provide a window into one of the world’s most fearsome symbols. —E.C.