with Dom Columba Marmion, an Irish Thomist. Raised to the rank of monsignor on 6 May 1887, Mercier founded the Higher Institute of Philosophy at the Louvain University in 1899, which was to be a beacon of neo-Thomist philosophy. He founded in 1894 and edited until 1906 the Revue Néoscholastique, and wrote in a scholastic manner on metaphysics, philosophy, and psychology. Several of his works were translated into English, German, Italian, Polish, and Spanish. His most important book was Les origines de la psychologie contemporaine (1897). Bishop and cardinal His reputation within his field gained the recognition of Pope Pius X, and Mercier was appointed as Archbishop of Mechelen and Primate of Belgium on 7 February 1906. He received his episcopal consecration on the following 25 March from Archbishop Antonio Vico, and took as his episcopal motto: Apostolus Jesu Christi. Mercier was created cardinal priest by Pope Pius X in the consistory of 15 April 1907. Three days later Pope Pius gave him his cardinal's ring and assigned him the titular church of S. Pietro in Vincoli. During the modernist controversy, Mercier was both progressive and antimodernist. He sought to assess the compatibility of Thomistic philosophy with rapidly developing scientific knowledge. He was a brilliant scholar, open to contemporary ideas and sufficiently respected that he was able to protect scholars at Louvain, such as Bollandist Hippolyte Delehaye, from accusations of "modernism". Through his influence, Mercier prevented Albin van Hoonacker's Les douze petits prophètes traduits et commentés ["The twelve minor prophets translated and annotated"] from being placed on the Index. Mercier was a close friend of Benedictine Lambert Beauduin and kept apprised of liturgical and ecumenical developments. From 1921 to 1926 he held regular conversations with Anglican theologians, notably Charles Wood, 2nd Viscount Halifax, foreshadowing the Church's future dialogue with the Anglicans. Anglicanism, Mercier believed, must be "united, not absorbed". Pope Benedict XV sent his portrait and a letter of whole-hearted support to Mercier in 1916, and at one point told him, "You saved the Church!" Mercier was one of the cardinal electors in the 1922 papal conclave, which selected Pope Pius XI. World War I German occupation In 1914 the German army attempted a surprise invasion of France by invading neutral Belgium. Mercier had to leave his see on 20 August of that same year to attend the funeral of the late Pius X, and participate in the following conclave