15 Then, indeed, will that most desirable result come about, that the character and conduct of individuals also will be reformed; for, just as from a rotten stock are produced healthless branches or worthless fruits, so do the ravages of a pestilence which ruins the household spread wide their cruel infection to the hurt and injury of individual citizens. On the other hand, when domestic society is fashioned in the mould of Christian life, each member will gradually grow accustomed to the love of religion and piety, to the abhorrence of false and harmful teaching, to the persuit of virtue, to obedience to elders, and to the restraint of the insatiable seeking after self interest alone, which so spoils and weakens the character of men. To this end it will certainly help not a little to encourage and promote those pious associations which have been established, in our own times especially, with so great profit to the cause of the Catholic religion.
Source: Inscrutabili Dei Consilio (Vatican.va)