Part — Wouters, Manual of Moral Theology
Part I. On the Existence of Extreme Unction
I. Extreme Unction is a true sacrament; this proposition is of faith from the Council of Trent: "If anyone says that Extreme Unction is not truly and properly a sacrament instituted by Christ our Lord, and promulgated by blessed James the Apostle; ... let him be anathema."1
Note. It is disputed at what time Extreme Unction was instituted. Some have thought that the anointing performed by the Apostles, of which Mark speaks,2 was Extreme Unction. But this opinion must be rejected, because the minister of that sacrament is a priest; the Apostles, however, were constituted priests afterwards, namely at the Lord's Supper. Most hold that this sacrament, which is the complement of Penance, was instituted after Christ's resurrection together with Penance.
2 "And they anointed with oil many sick persons and healed them" (Mark 6:13).
II. Extreme Unction, even in the case in which several anointings and prayers are used, is only one sacrament; otherwise the dogma concerning the sevenfold number of the sacraments would not stand. This, however, is explained in different ways by different authors. According to some, the diverse anointings and prayers taken together signify and produce one complete effect; but the effect is produced either by parts, as Scotus teaches,1 or after the last anointing has been performed, as St. Thomas holds (Supplement, q. 30, a. 1, ad 3; cf. St. Alphonsus, VI, 707, qu. 2). According to others, the first anointing together with the partial form signifies and effects the entire effect, while the other anointings are regarded only as sacramentals (n. 570).
1 According to Mastrius, Scotus supposes that the individual actions have their own partial effects. For Scotus says, In IV Sent., dist. 23, at the end, ad 2, that this sacrament is indeed one by unity of integrity, but not by unity of indivisibility, just as its effect is not one indivisibly, because it is not the remission of one venial sin, but one by the unity of the full remission of all venial sins (Gaude, in St. Alphonsus, VI, 707).