Scholion

I. The doctrine has been defined by Trent, can. 8, that the Church does not err when, for many causes, it decrees that separation between spouses as to bed, or as to cohabitation, can be made for a definite or indefinite time.

In this matter it must be observed that those causes are reduced to three genera, that is, mutual consent, grave danger of soul or body, and crime. Crime indeed is distinguished as threefold, namely, adultery of the other party, apostasy from the true religion, whether through unbelief or through heresy, and seduction to sin, so that the one who is seduced is placed in danger of sinning. But this third returns to the second of the three genera. Moreover the first of these crimes is a cause of separation proper and intrinsic to marriage; but the other causes are common to other societies, and therefore, as it were, extrinsic to marriage. Nevertheless, unbelief, which is also called spiritual fornication, is especially against the good of marriage, which is offspring to be educated for the worship of God (q. LXII, a. 1, ad 3). Likewise, as regards the first crime, one act suffices, and it is the reason for perpetual separation, so that, even if the sinning spouse comes to his senses, the innocent party is not bound to return, unless he himself should fornicate (c. Ex literis, De Divortiis), but can, for example, vow perpetual continence or enter religion. But in the other crimes a certain custom is required, and they are causes of themselves temporal; when these cease, the innocent party is bound to be reconciled to the penitent (c. De illa, De Divortiis; cf. St. Thomas, l. c.). Then it must be observed that separation as to bed, since it is a private matter, can be made by one's own will; but separation as to habitation, since it is a public matter, ought to be made by the judgment of the Church (c. Porro, De Divortiis).

II. Now, that separation as to bed or habitation can lawfully be made for these causes, while the conjugal bond remains, is proved: 1. because there is no repugnance that, while dominion is retained, the use of the thing, or the proximate right to use, should be lost for some causes, whether from one's own will or from the disposition of law; 2. because from the Gospel we are taught that divorce of this sort can be made for these causes. For divorce which is made from mutual consent is indicated as lawful by those words of Christ, Matt. XIX, 29: Everyone who has left house ... wives or children, etc., will receive a hundredfold and will possess eternal life. Cf. the title de Conversione coniugatorum. The Apostle supposes that divorce from the cause of crime is lawful in 1 Cor. VII, 11, where, as we have already noted, there is discourse about departure for a just cause. Christ proves the cause of fornication, Matt. V, 32, if the sentence of Christ is taken according to the more common interpretation, where the dismissal which is granted is not as to the bond, because he who marries the dismissed woman commits adultery; but some dismissal is granted on account of fornication. For he who on account of it dismisses his wife is not imputed the crime of adultery which his wife is afterward going to commit, as it is imputed to him who dismisses an innocent woman; therefore he does not sin, but acts lawfully. Moreover the dismissal is not only separation as to bed, but also as to habitation. Paul indicated generally the cause of apostasy from the faith with danger of the perversion of the other party in Titus III, 10. Cf. c. ult., De Convers. Coniug. and c. 2, De Divortiis. Christ proves the cause of seduction to sin in Matt. XVIII, 9: If your eye scandalizes you, pluck it out and cast it from you, which reason proves is to be understood also of a spouse. Natural reason proves the cause of grave bodily danger, such as danger of life, mutilation, and frequent intolerable cruelties; cf. c. 13, at the end, De Restitutione Spoliatorum.

Accordingly this doctrine is not new, both because it is handed down in the Gospel and by the Apostle, and because it is handed down by the Fathers, as can be established from their testimonies cited above. The same is confirmed by canon law and the continual practice of the Church.

III. Nor is it opposed to the Gospel, which mentions one cause, fornication, if that interpretation is true. For that mention is not exclusive, since other causes are sufficiently indicated elsewhere in the Gospel; but that cause alone is explicitly indicated because Christ wished to signify the proper and intrinsic cause, and one which is also perpetual, since the other causes are not of themselves perpetual, but when they cease, the spouses are to be recalled. Nor is it opposed to the moral law that the bond remains after separation has been made; for 1. the grace of God is always present, by which this loss can be patiently tolerated; 2. if the evils which can proceed from the perpetuity of the bond and from its dissolution are compared, those which would arise from dissolution are much greater, as being against the greater good, that is, of family, society, religion, and against the good of the Sacrament. Cf. Thesis XXIII.

Seek the rest among the canonists.