Pope Pius X (ItalianPio X; born Giuseppe Melchiorre Sarto[a]; 2 June 1835 – 20 August 1914) was head of the Catholic Church from August 1903 to his death in 1914. Pius X is known for vigorously opposing modernist interpretations of Catholic doctrine, promoting liturgical reforms and scholastic philosophy and theology. He initiated the preparation of the 1917 Code of Canon Law, the first comprehensive and systemic work of its kind. He is venerated as a saint in the Catholic Church.

Pius X was devoted to the Marian title of Our Lady of Confidence; while his papal encyclical Ad diem illum took on a sense of renewal that was reflected in the motto of his pontificate.[5] He advanced the Liturgical Movement by formulating the principle of participatio actuosa (active participation) of the faithful in his motu proprio Tra le sollecitudini (1903), he encouraged the frequent reception of holy communion, and he lowered the age for First Communion, which became a lasting innovation of his papacy.[6] Like his predecessors, he promoted Thomism as the principal philosophical method to be taught in Catholic institutions. As Roman pontiff, he vehemently opposed modernism and various nineteenth-century philosophies, which he viewed as an import of secular errors incompatible with Catholic dogma.[7] He also reformed the Roman Curia (Apostolic Constitution Sapienti consilio, 1908).