Indeed, how many and how important are the benefits which flow from the indissolubility of matrimony cannot escape anyone who gives even a brief consideration either to the good of the married parties and the offspring or to the welfare of human society. First of all, both husband and wife possess a positive guarantee of the endurance of this stability which that generous yielding of their persons and the intimate fellowship of their hearts by their nature strongly require, since true love never falls away. Besides, a strong bulwark is set up in defense of a loyal chastity against incitements to infidelity, should any be encountered either from within or from without; any anxious fear lest in adversity or old age the other spouse would prove unfaithful is precluded and in its place there reigns a calm sense of security. Moreover, the dignity of both man and wife is maintained and mutual aid is most satisfactorily assured, while through the indissoluble bond, always enduring, the spouses are warned continuously that not for the sake of perishable things nor that they may serve their passions, but that they may procure one for the other high and lasting good have they entered into the nuptial partnership, to be dissolved only by death. In the training and education of children, which must extend over a period of many years, it plays a great part, since the grave and long enduring burdens of this office are best borne by the united efforts of the parents. Nor do lesser benefits accrue to human society as a whole. For experience has taught that unassailable stability in matrimony is a fruitful source of virtuous life and of habits of integrity. Where this order of things obtains, the happiness and well being of the nation is safely guarded; what the families and individuals are, so also is the State, for a body is determined by its parts. Wherefore, both for the private good of husband, wife and children, as likewise for the public good of human society, they indeed deserve well who strenuously defend the inviolable stability of matrimony.
The advocates of the neo-paganism of today have learned nothing from the sad state of affairs, but instead, day by day, more and more vehemently, they continue by legislation to attack the indissolubility of the marriage bond, proclaiming that the lawfulness of divorce must be recognized, and that the antiquated laws should give place to a new and more humane legislation. Many and varied are the grounds put forward for divorce, some arising from the wickedness and the guilt of the persons concerned, others arising from the circumstances of the case; the former they describe as subjective, the latter as objective; in a word, whatever might make married life hard or unpleasant. They strive to prove their contentions regarding these grounds for the divorce legislation they would bring about, by various arguments. Thus, in the first place, they maintain that it is for the good of either party that the one who is innocent should have the right to separate from the guilty, or that the guilty should be withdrawn from a union which is unpleasing to him and against his will. In the second place, they argue, the good of the child demands this, for either it will be deprived of a proper education or the natural fruits of it, and will too easily be affected by the discords and shortcomings of the parents, and drawn from the path of virtue. And thirdly the common good of society requires that these marriages should be completely dissolved, which are now incapable of producing their natural results, and that legal reparations should be allowed when crimes are to be feared as the result of the common habitation and intercourse of the parties. This last, they say must be admitted to avoid the crimes being committed purposely with a view to obtaining the desired sentence of divorce for which the judge can legally loose the marriage bond, as also to prevent people from coming before the courts when it is obvious from the state of the case that they are Iying and perjuring themselves -- all of which brings the court and the lawful authority into contempt. Hence the civil laws, in their opinion, have to be reformed to meet these new requirements, to suit the changes of the times and the changes in men's opinions, civil institutions and customs. Each of these reasons is considered by them as conclusive, so that all taken together offer a clear proof of the necessity of granting divorce in certain cases. Others, taking a step further, simply state that marriage, being a private contract, is, like other private contracts, to be left to the consent and good pleasure of both parties, and so can be dissolved for any reason whatsoever. (Papal Encyclical, Casti Connubii, 31 December 1930).