«RERUM ECCLESIAE» — Thus begins the encyclical letter of Pius XI of 28 Feb. 1926, addressed to recall in writing the teachings of the Vatican Missionary Exhibition of the Holy Year 1925 (Syllog de Propaganda Fide, Rome 1909, no. 120, pp. 240-258).
In the introduction, the Holy Father states that the Church, despite varying success, has always sought to win for Jesus Christ those who were far from Him; he then recalls the beneficial effects of the letter of Benedict XV *Maximun illud* (q.v.), the Vatican Missionary Exhibition, and the establishment of the Lateran Missionary Museum, and, noting with sorrow that many still remain unbelievers, admonishes all Christians of their duties in this matter and asks for their generous help. The first part of the encyclical speaks of the missionary duty in general, which is founded on the virtue of charity, and of the particular missionary duty, which consists chiefly in praying for the missions and in arousing and fostering vocations to the apostolate. To this end, he recommends that in every diocese the Missionary Union of the Clergy (q.v.) and the three Pontifical Missionary Works (q.v.) be established and organized. The second part reminds mission superiors of the duty to form a numerous and capable indigenous clergy by founding seminaries and of instructing catechists well. He advises the establishment of indigenous religious congregations and the introduction of contemplative Orders. He then gives precise directives on the manner of distributing missionary forces so as to ensure a progressive conquest of territory.
At the end, Pius XI recommends to missionary Ordinaries, in case of a shortage of missionaries, to call upon new workers even from other religious families. To the religious congregations, he recalls that the territories are entrusted to them at the pleasure of the Holy See, which may freely assign them to other institutes, divide them, and entrust them to the indigenous clergy or to other congregations. Lastly, he exhorts all bishops to assist the missions with the means suggested.
«EVANGELII PRAECONES» — To the same missionary subject refers the encyclical *Evangelii praecones* of Pius XII of 2 June 1951 (AAS, 43 [1951], pp. 497-558), which may be divided into three parts.
The first, after a brief introduction in which it explains the occasion that gave rise to the publication of the encyclical, speaks of the progress achieved in the past twenty-five years in the number of conversions, in the ecclesiastical organization of various territories, and in the regulation of missionary cooperation. It then recalls that in some territories of Asia persecution rages and how