"On the part of the penitent, the sacrament of Reconciliation requires sincere sorrow, a formally complete accusation of mortal sins, and the resolution, with the help of God, not to fall into sin again. In general, it is not necessary for the confessor to investigate concerning sins committed in invincible ignorance of their evil, or due to an inculpable error of judgment. Although these sins are not imputable, they do not cease, however, to be an evil and a disorder. This also holds for the objective evil of contraception, which introduces a pernicious habit into the conjugal life of the couple. It is therefore necessary to strive in the most suitable way to free the moral conscience from those errors which contradict the nature of conjugal life as a total gift"