106 Certainly, if the latter day subverters of marriage are entirely devoted to misleading the minds of men and corrupting their hearts, to making a mockery of matrimonial purity and extolling the filthiest of vices by means of books and pamphlets and other innumerable methods, much more ought you, Venerable Brethren, whom "the Holy Ghost has placed as bishops, to rule the Church of God, which He hath purchased with His own blood," to give yourselves wholly to this, that through yourselves and through the priests subject to you, and, moreover, through the laity welded together by Catholic Action, so much desired and recommended by Us, into a power of hierarchical apostolate, you may, by every fitting means, oppose error by truth, vice by the excellent dignity of chastity, the slavery of covetousness by the liberty of the sons of God, that disastrous ease in obtaining divorce by an enduring love in the bond of marriage and by the inviolate pledge of fidelity given even to death.
Source: Casti Connubii (Vatican.va)