When Christ's faithful strive to confess all the sins that they can remember, they undoubtedly place all of them before the divine mercy for pardon. But those who fail to do so and knowingly with hold some, place nothing before the divine goodness for remission through the mediation of the priest, "for if the sick person is too ashamed to show his wound to the doctor, the medicine cannot heal what it does not know."
Council of Trent (1551): DS 1680 (ND 1626); cf. St. Jerome, In Eccl. 10,11:PL 23:1096.