Pope Leo XIII, who served from 1878 to 1903, led the church into the modern world, emphasizing its moral authority beyond national boundaries. He defended the rights of working people and affirmed the value of science.

When the Museum of Modern Art debuted in a Manhattan townhouse in 1929, it faced incomprehension from audiences still uncomfortable with abstract art. When the Centre Georges Pompidou inaugurated its inside-out home in Paris in 1977, philosophers …