From Pope St. John Paul II’s Apostolic Exhortation Reconciliatio et Pænitentia (1984):
The third conviction, which is one that I wish to emphasize, concerns the realities or parts which make up the sacramental sign of forgiveness and reconciliation. Some of these realities are acts of the penitent, of varying importance but each indispensable either for the validity, the completeness or the fruitfulness of the sign.
First of all, an indispensable condition is the rectitude and clarity of the penitent’s conscience. People cannot come to true and genuine repentance until they realize that sin is contrary to the ethical norm written in their in most being;183 until they admit that they have had a personal and responsible experience of this contrast; until they say not only that “sin exists” but also “I have sinned”; until they admit that sin has introduced a division into their consciences which then pervades their whole being and separates them from God and from their brothers and sisters. The sacramental sign of this clarity of conscience is the act traditionally called the examination of conscience, an act that must never be one of anxious psychological introspection, but a sincere and calm comparison with the interior moral law, with the evangelical norms proposed by the church, with Jesus Christ himself, who is our teacher and model of life, and with the heavenly Father, who calls us to goodness and perfection.184
But the essential act of penance, on the part of the penitent, is contrition, a clear and decisive rejection of the sin committed, together with a resolution not to commit it again,185 out of the love which one has for God and which is reborn with repentance. Understood in this way, contrition is therefore the beginning and the heart of conversion, of that evangelical metanoia which brings the person back to God like the prodigal son returning to his father, and which has in the sacrament of penance its visible sign and which perfects attrition. Hence “upon this contrition of heart depends the truth of penance.”186
183 Even the pagans recognized the existence of “divine” moral laws which have “always” existed and which are written in the depths of the human heart, cf Sophocles (Antigone, w. 450-460) and Aristotle (Rhetor., Book I, Chap. 15, 1375 a-b).
184 On the role of conscience cf what I said at the general audience of March 14, 1984, 3: Insegnamenti VII, 1 (1984), 683.
185 Cf Council of Trent, Session XIV, De Sacramento Pœnitentiæ, Chap. 4 De Contritione: Conciliorum Œcumenicorum Decreta, ed. cit., 705 (Denzinger, Heinrich, and Adolf Schönmetzer, Enchiridion symbolorum definitionum et declarationum de rebus fidei et morum [DS] 1676-1677). Of course, in order to approach the sacrament of penance it is sufficient to have attrition, or imperfect repentance, due more to fear than to love. But in the sphere of the sacrament, the penitent, under the action of the grace that he receives, ex attrito fit contritus, since penance really operates in the person who is well disposed to conversion in love: cf Council of Trent, ibid., ed. cit., 705 (DS 1678).
186 Ordo Pænitentiæ, 6c.
— Reconciliatio et Pænitentia 31