Desio 1857-Vatican City 1939. As Pius XI, 259th pope of the Catholic Church, seminaries in Seveso and Monza, diploma from the Liceo Parini in Milan, Franciscan Tertiary, theological studies at the Seminario Maggiore in Milan, priest in Rome from 1879. Prefect of the Biblioteca Ambrosiana from 1907, ecclesiastical history scholar, three degrees, passion for literature (Dante and Manzoni), worked with the geologist Don Giuseppe Mercalli. Professor of Mathematics in the minor seminary, professor of Hebrew, chaplain of the Cenacolo in Milan. Held rigid views in the debate between Catholics and liberals, founded Il Rinnovamento magazine in 1907. A keen mountaineer, he climbed the Matterhorn and the Mont Blanc. Prefect of the Vatican Library from 1914, then Apostolic nuncio in Poland and Lithuania. Laid the bases for the future concordat signed in Latvia, Archbishop of Milan from 1921. Elected Pope in 1922, he wrote several encyclicals at a time made difficult by relations with Nazism, Fascism, Communism and the Spanish Civil War.