This morning, two activists pasted a photograph of a Palestinian mother and child over the protective glass of Pablo Picasso’s 1901 painting Motherhood (La Maternité) at the National Gallery in London, in a bid for attention to the dangers faced by families in Gaza. After pasting the image, Jai Halai, a 23-year-old employee at the National Health Service, and Monday-Malachi Rosenfeld, a 21-year-old student, poured red paint on the gallery floor before their arrest. A video posted to the Youth Demand X page captures Rosenfeld seated in front of the faux-blood splatter, saying to a crowd of onlookers, “All of...