Theory and practice of the confessional by Caspar Erich Schieler, Richard Frederick Clarke
With respect to the obligation of the integrity of confession we may lay down the following propositions: —
I. It is of divine precept to confess all mortal sins committed after Baptism. 1. This follows from the words by which Christ instituted the Sacrament; by them He gave the Sacrament a judicial character. So teaches the Council of Trent. (Sess. XIV. cp. 5, De Confessione.) From the institution of the Sacrament of Penance "the universal Church has always recognised that the complete confession of sins was also instituted by Our Lord, and is necessary jure divino for all who have sinned after Baptism. For Our Lord Jesus Christ when about to ascend into heaven left the priests as His vicars and judges, by whom all mortal sins into which the faithful had fallen were to be judged, that in virtue of the power of the keys they might pronounce sentence of forgiveness or retention." The priest is therefore a judge, and as judge should pronounce the absolution. But the sentence of a judge is valid only when it turns on the facts of the case; hence a knowledge of the latter is required on the part of the judge. In consequence the confessor, in order to pronounce a valid sentence, must know intimately the facts of the case, the state of the sinner. Now the facts of the case are the mortal sins of the penitent; hence the confessor must be made acquainted with these; and as he can only learn them from the penitent himself, the latter is bound to make a complete statement of them.