The Souls in Purgatory by Rev. Fr. Frederick Faber

Of the soul after the Particular Judgment, Father Faber says:  The moment that in His sight it perceives its own unfitness for Heaven, it wings its voluntary flight to Purgatory, like a dove to her proper nest in the shadows of the forest. No sooner has a soul, with the guilt of no mortal sin upon it, but owing to God a debt of temporal punishment, issued from the world, and been judged, than it perceives itself to be confirmed in grace and charity (according to St. Catherine of Genoa). It is incapable either of sinning or of meriting any more; and it is destined by an eternal and immutable decree to enter one day as a queen into the Kingdom of the Blessed, to see, to love, and to enjoy God, the perpetual Fountain of all felicity.

In that instant all the sins of its past are represented to the soul, whether mortal or venial, even though they have been remitted in lifetime by contrition and the Sacrament of Penance. The reason of this exhibition of sins is, she teaches us, to enable the soul in that moment, by an act, no longer indeed meritorious, but nevertheless a real act of the will, to detest all its sins afresh, and especially those venial sins for which it had not contrition in lifetime, either through the weakness of an imperfect heart, or through the accident of a sudden death, that so it may be strictly true, that no sin whatever is pardoned unless the sinner makes an act of detestation of it.

After this momentary view of sins and formal detestation of them, the soul perceives in itself their evil consequences and malignant legacies, and these form what St. Catherine calls the impediment of seeing God. The rust of sin, she says, is the impediment, and the fire keeps consuming the rust; and as a thing which is covered cannot correspond to the reverberation of the sun's rays, so, if the covering be consumed, the thing is at length laid open to the sun.

As soon as the soul perceives itself to be acceptable to God, and constituted heir of Paradise, but unable, because of this impediment, to take immediate possession of its inheritance, it conceives an intense desire to be rid of this hindrance, this double obligation of guilt and punishment. But knowing that Purgatory alone can consume these two obligations, and that it is for that very end God condemns the soul to fire, it desires itself to endure the punishment.