Sancta Dei Civitas §5

⁵ But both of these societies yield support to that older one entitled the Society of the Propagation of the Faith, and, united with it in a friendly alliance, aim at the same end, relying on the alms and prayers of the Christian nations: for all have the same purpose in view, namely, by the diffusion of the Gospel light to bring the largest possible number of those outside the Church to the knowledge and worship of God and Jesus Christ Whom He has sent. Hence Our predecessor Pius IX., as We have intimated, has in Apostolic letters commended these two institutions and liberally enriched them with sacred Indulgences.