Sancta Dei Civitas §7

⁷ On the other hand many and grave necessities weigh upon and oppress the Apostolic missions, since the number of sacred labourers decreases every day, nor do We find that as many or as zealous missionaries replace those whom death has carried off, whom age has enfeebled, or whom work has broken down. For We see Religious communities, whence a large number of missionaries came forth, dissolved by iniquitous laws, the clergy torn away from the altar and obliged to undergo military service, and the goods of both orders of clergy almost everywhere put up to sale and proscribed.