Article — Noldin, Summa of Moral Theology
Article II. On the Necessity of Contrition.
252. Whether it is necessary and when. Penance is simply necessary for salvation to a man who has committed grave sin (n. 241); but it alone does not suffice, unless either charity or the sacrament of penance is added. In this place the necessity of perfect contrition must be considered insofar as it is the means of reconciling oneself with God and of obtaining the grace of justification.
For a sinner, perfect contrition is necessary by necessity of means and of precept, both natural and divine positive, for obtaining salvation, unless there is an occasion of receiving the sacrament.1 a. The effect of contrition, namely justification, is simply necessary for salvation for those who are constituted in mortal sin; therefore by the same necessity the means for obtaining the same effect is also necessary. b. The natural law obliges one to use the means necessary for salvation; but in Sacred Scripture penance is expressly commanded many times (n. 241). Nevertheless the precept of perfect contrition obliges only in defect of the sacrament: for in the new law perfect contrition is no longer absolutely necessary for obtaining justification, but attrition with the sacrament of baptism or of penance suffices, and this by the will of Christ the Lord, who by instituting the sacraments of the dead gave men a new means of obtaining eternal salvation. Therefore he who either intends to be justified through the sacrament of baptism or penance, or has already been justified, is not bound by the precept of contrition.
Perfect contrition is of itself necessary at death: for if contrition is a means necessary for salvation, it must certainly be used at that time after which it can no longer be used.
Therefore he who is in certain or probable danger of death and does not have the opportunity of receiving the sacrament of penance is bound to elicit perfect contrition; yet if he has received the sacrament with attrition, he is not further bound to elicit an act of perfect contrition, since he is now certainly justified. Nevertheless it is expedient that the dying be stirred up, as far as possible, to eliciting acts of perfect charity and contrition.2
Perfect contrition is of itself necessary when the precept of reconciling oneself with God urges and there is no occasion of instituting confession (n. 217).
Perfect contrition is accidentally necessary in these cases: a. if a consecrated minister existing in the state of mortal sin must solemnly administer and confect a sacrament, and there is no supply of a confessor; b. if someone existing in mortal sin must receive a sacrament of the living and either cannot or will not confess; c. if someone existing in mortal sin suffers grave temptations, which he thinks he cannot overcome unless, having been converted to God, he obtains greater helps of grace: for he must employ the means necessary for avoiding sin.
1 Council of Trent, sess. 14, c. 4.
2 Cf. W. Lerch, Das letzte Mittel (Warnsdorf, Opitz); J. von den Driesch, Die vollkommene Reue, ein goldener Himmelsschlussel (Koln, Bachem), who discuss the nature of contrition and the way of eliciting it in a manner accommodated to the capacity of the common people.