Pope Leone XIII

Pope Leone XIII, who served from 1878 to 1903, is best known for his encyclical 'Rerum Novarum,' which addressed the conditions of the working class and laid the groundwork for modern Catholic social teaching. His papacy emphasized the importance of social justice, the rights of workers, and the need for the Church to engage with contemporary social and political issues, marking a significant shift in the Church's approach to the modern world.