Rerum Novarum (1891)
Pope Leo XIII published Rerum Novarum, addressing the industrial revolution. He defended workers' right to fair wages, condemned both unrestrained capitalism and revolutionary socialism, and argued that the state has a duty to regulate employers in the common interest.
The text became the foundation of modern Catholic social teaching. It legitimized Catholic labor unions across Europe and Latin America.
Its framework shaped welfare-state debates for more than a century and is still cited by Catholic legislators when arguing for labor protection.
Leo XIV signed Magnifica Humanitas on Rerum Novarum's 135th anniversary and took his papal name from its author. The deliberate parallel frames AI as a comparable break in how humans organize work and power.
