What significant document did Pope Leo XIII write?

Pope Leo XIII is best known for writing the encyclical "Rerum Novarum," which addresses the condition of the working classes and the rights of labor. However, among the options available, "Of New Things" (typically known by its Latin title "Nouveau") does not pertain to Pope Leo XIII's significant contributions.

The document "On the Development of Peoples" is associated with Pope Paul VI, while "Veritatis Splendor" and "Humanae Vitae" are linked to Pope John Paul II and Pope Paul VI, respectively. Pope Leo XIII's encyclical "Rerum Novarum," in contrast, was groundbreaking as it was one of the first papal teachings on social justice, addressing issues such as workers' rights, the dangers of socialism, and the importance of private property.

Understanding that context helps recognize the impact of Pope Leo XIII’s teachings, even if the specific document titled "Of New Things" does not actually correspond to his work.