Casti Connubii §110

¹¹⁰ Even the very best instruction given by the Church, however, will not alone suffice to bring about once more conformity of marriage to the law of God; something more is needed in addition to the education of the mind, namely a steadfast determination of the will, on the part of husband and wife, to observe the sacred laws of God and of nature in regard to marriage. In fine, in spite of what others may wish to assert and spread abroad by word of mouth or in writing, let husband and wife resolve: to stand fast to the commandments of God in all things that matrimony demands; always to render to each other the assistance of mutual love; to preserve the honor of chastity; not to lay profane hands on the stable nature of the bond; to use the rights given them by marriage in a way that will be always Christian and sacred, more especially in the first years of wedlock, so that should there be need of continency afterwards, custom will have made it easier for each to preserve it. In order that they may make this firm resolution, keep it and put it into practice, an oft-repeated consideration of their state of life, and a diligent reflection on the sacrament they have received, will be of great assistance to them. Let them constantly keep in mind, that they have been sanctified and strengthened for the duties and for the dignity of their state by a special sacrament, the efficacious power of which, although it does not impress a character, is undying. To this purpose we may ponder over the words full of real comfort of holy Cardinal Robert Bellarmine, who with other well-known theologians with devout conviction thus expresses himself: "The sacrament of matrimony can be regarded in two ways: first, in the making, and then in its permanent state. For it is a sacrament like to that of the Eucharist, which not only when it is being conferred, but also whilst it remains, is a sacrament; for as long as the married parties are alive, so long is their union a sacrament of Christ and the Church."