The First Purification, namely, from Mortal Sin.
THE first purification to be made is from sin;—the means whereby to make it, the sacrament of penance. Seek the best confessor within your reach, use one of the many little books written in order to help the examination of conscience.  Read some such book carefully, examining point by point wherein you have sinned, from the first use of your reason to the present time. And if you mistrust your memory, write down the result of your examination. Having thus sought out the evil spots in your conscience, strive to detest them, and to reject them with the greatest abhorrence and contrition of which your heart is capable;—bearing in mind these four things:—that by sin you have lost God’s Grace, rejected your share in Paradise, accepted the pains of Hell, and renounced God’s Eternal Love. You see, my child, that I am now speaking of a general confession of your whole life, which, while I grant it is not always necessary, I yet believe will be found most helpful in the beginning of your pursuit after holiness, and therefore I earnestly advise you to make it. Not unfrequently the ordinary confessions of persons leading an everyday life are full of great faults, and that because they make little or no preparation, and have not the needful contrition. Owing to this deficiency such people go to confession with a tacit intention of returning to their old sins, inasmuch as they will not avoid the occasions of sin, or take the necessary measures for amendment of life, and in all such cases a general confession is required to steady and fix the soul. But, furthermore, a general confession forces us to a clearer selfknowledge, kindles a wholesome shame for our past life, and rouses gratitude for God’s Mercy, Which has so long waited patiently for us;—it comforts the heart, refreshes the spirit, excites good resolutions, affords opportunity to our spiritual Father for giving the most suitable advice, and opens our hearts so as to make future confessions more effectual. Therefore I cannot enter into the subject of a general change of life and entire turning to God, by means of a devout life, without urging upon you to begin with a general confession.
(Introduction to the Devout Life by St. Francis de Sales. Public Domain.)