3 At the Missionary Exhibition men have been deeply impressed in seeing the increasing zeal of the Church for the spread of the kingdom of her Spouse to the most far distant regions of the earth. They have seen how many countries have been won to the Catholic name through the unremitting labor and self-sacrifice of missionaries, and the vastness of the regions which have yet to be subjected to the sweet and saving yoke of our King. All those who in the course of the Holy Year have thronged to this city under the leadership of their Bishops or priests had but one aim - namely, to expiate their sins - and at the tombs of the Apostles and in Our Presence to promise loyalty to the rule of Christ.
Source: Quas Primas (Vatican.va)