The souls in purgatory desire one thing only: to be consumed in the love of God. This ardent charity gradually purifies their imperfections and draws them ever closer to God until they obtain Him fully.
What will purgatory be like? Perhaps the greatest description of what a soul will experience in purgatory has been given to us by St. Catherine of Genoa.
St. Catherine was given the special grace to experience in this life, over the span of a few years, the actual sufferings of purgatory in her soul. This enabled her to give the Church a detailed account of the condition of the Holy Souls in Purgatory based on her personal experience.
Her masterful work, Treatise on Purgatory, is excerpted below.
THE SOULS IN PURGATORY LOVE GOD ALONE
This holy soul, while still in the flesh, was placed in the purgatory of the burning love of God, in whose flames she was purified from every stain of sin, so that when she passed from this life she might be ready to enter the presence of God, her most sweet love.
By means of that flame of love she comprehended in her own soul the condition of the souls of the faithful in purgatory, where they are purified from the rust and stain of sins, from which they have not been cleansed in this world…
As far as I can see, the souls in purgatory can have no choice but to be there; this God has most justly ordained by his divine decree… They are so contented with the divine dispositions in their regard; and with doing all that is pleasing to God in that way which he chooses, that they cannot think of themselves, though they may strive to do so.
They see nothing but the operation of the divine goodness which is so manifestly bringing them to God that they can reflect neither on their own profit nor on their hurt. Could they do so, they would not be in pure charity…
… Being established in charity, they can never deviate therefrom by any defect, and have no will or desire, save the pure will of pure love, and can swerve from it in nothing. They can neither commit sin, nor merit by refraining from it.
THE SOULS IN PURGATORY EXPERIENCE BOTH PEACE AND SUFFERING
There is no peace to be compared with that of the souls in purgatory, save that of the saints in paradise and this peace is ever augmented by the inflowing of God into these souls, which increases in proportion as the impediments to it are removed.
The rust of sin is the impediment, and this the fire continually consumes, so that the soul in this state is continually opening itself to admit the divine communication…
In purgatory the flames incessantly consume [the rust of sin], and as it disappears, the soul reflects more and more perfectly the true sun who is God. Its contentment increases as this rust wears away, and the soul is laid bare to the divine ray, and thus one increases and the other decreases until the time is accomplished.
The pain never diminishes, although the time does, but as to the will, so united is it to God by pure charity, and so satisfied to be under his divine appointment, that these souls can never say their pains are pains. On the other hand, it is true that they suffer torments which no tongue can describe nor any intelligence comprehend…
SEPARATION FROM GOD IS THE GREATEST PAIN OF PURGATORY
The source of all suffering is either original or actual sin. God created the soul pure, simple, free from every stain… when [God] finds a soul that is returning to the purity and simplicity in which she was created, he … kindles in her a fire of charity so powerful and vehement, that it is insupportable to the soul to find and obstacle between her and [God]; and the clearer vision she has of these obstacles the greater is her pain.
Since the souls in purgatory are freed from the guilt of sin, there is no barrier between them and God save only the pains they suffer, which delay the satisfaction of their desire.
And when they see how serious is even the slightest hindrance, which the necessity of justice causes to check them, a vehement flame kindles within them, which is like that of hell…
THE SOULS IN PURGATORY EXPERIENCE BOTH CONTENTMENT AND YEARNING
The souls in purgatory are entirely conformed to the will of God; therefore, they correspond with his goodness, are contented with all that he ordains, and are entirely purified from the guilt of their sins.
They are pure from sins, because they have in this life abhorred them and confessed them with true contrition, and for this reason God remits their guilt, so that only the stains of sin remain, and these must be devoured by the fire. Thus freed from guilt and united to the will of God, they see him clearly according to that degree of light which he allows them, and comprehend how great a good is the fruition of God, for which all souls were created.
Moreover, these souls are in such close conformity to God, and are drawn so powerfully toward him by reason of the natural attraction between him and the soul, that no illustration or comparison could make this impetuosity understood…
… the souls in purgatory have an assured hope of seeing him and of being entirely satisfied; and therefore they endure all hunger and suffer all pain until that moment when they enter into eternal possession of… Jesus Christ, our Lord, our Savior, and our Love.
THE SOUL ENTERS PURGATORY WILLINGLY OUT OF LOVE FOR GOD