Old news by now, but worth discussing.
From the Pope's catechetical address at the General Audience of January 12, 2011:
Catherine's thought on purgatory, for which she is particularly known, is condensed in the last two parts of the book mentioned at the beginning: "Treatise on Purgatory" and "Dialogues on the Soul and Body." It is important to observe that, in her mystical experience, Catherine never had specific revelations on purgatory or on souls that are being purified there. However, in the writings inspired by our saint purgatory is a central element, and the way of describing it has original characteristics in relation to her era. The first original feature refers to the "place" of the purification of souls. In her time [purgatory] was presented primarily with recourse to images connected to space: There was thought of a certain space where purgatory would be found. For Catherine, instead, purgatory is not represented as an element of the landscape of the core of the earth; it is a fire that is not exterior but interior. This is purgatory, an interior fire.
The saint speaks of the soul's journey of purification to full communion with God, based on her own experience of profound sorrow for the sins committed, in contrast to the infinite love of God (cf. Vita Mirabile, 171v). We have heard about the moment of her conversion, when Catherine suddenly felt God's goodness, the infinite distance of her life from this goodness and a burning fire within her. And this is the fire that purifies, it is the interior fire of purgatory. Here also there is an original feature in relation to the thought of the era. She does not begin, in fact, from the beyond to narrate the torments of purgatory -- as was usual at that time and perhaps also today -- and then indicate the path for purification or conversion. Instead our saint begins from her own interior experience of her life on the path to eternity. The soul, says Catherine, appears before God still bound to the desires and the sorrow that derive from sin, and this makes it impossible for it to enjoy the Beatific Vision of God. Catherine affirms that God is so pure and holy that the soul with stains of sin cannot be in the presence of the Divine Majesty (cf. Vita Mirabile, 177r). And we also realize how far we are, how full we are of so many things, so that we cannot see God. The soul is conscious of the immense love and perfect justice of God and, in consequence, suffers for not having responded correctly and perfectly to that love, and that is why the love itself of God becomes a flame. Love itself purifies it from its dross of sin.
The saint speaks of the soul's journey of purification to full communion with God, based on her own experience of profound sorrow for the sins committed, in contrast to the infinite love of God (cf. Vita Mirabile, 171v). We have heard about the moment of her conversion, when Catherine suddenly felt God's goodness, the infinite distance of her life from this goodness and a burning fire within her. And this is the fire that purifies, it is the interior fire of purgatory. Here also there is an original feature in relation to the thought of the era. She does not begin, in fact, from the beyond to narrate the torments of purgatory -- as was usual at that time and perhaps also today -- and then indicate the path for purification or conversion. Instead our saint begins from her own interior experience of her life on the path to eternity. The soul, says Catherine, appears before God still bound to the desires and the sorrow that derive from sin, and this makes it impossible for it to enjoy the Beatific Vision of God. Catherine affirms that God is so pure and holy that the soul with stains of sin cannot be in the presence of the Divine Majesty (cf. Vita Mirabile, 177r). And we also realize how far we are, how full we are of so many things, so that we cannot see God. The soul is conscious of the immense love and perfect justice of God and, in consequence, suffers for not having responded correctly and perfectly to that love, and that is why the love itself of God becomes a flame. Love itself purifies it from its dross of sin.
Theological and mystical sources typical of the era can be found in Catherine's work. Particularly there is an image from Dionysius the Areopagite: that of the golden thread that unites the human heart with God himself. When God has purified man, he ties him with a very fine thread of gold, which is his love, and attracts him to himself with such strong affection that man remains as "overcome and conquered and altogether outside himself." Thus the human heart is invaded by the love of God, which becomes the only guide, the sole motor of his existence (cf. Vita Mirabile, 246rv). This situation of elevation to God and of abandonment to his will, expressed in the image of the thread, is used by Catherine to express the action of the divine light on souls in purgatory, light that purifies them and elevates them to the splendors of the shining rays of God (cf. Vita Mirabile, 179r).
Dear friends, the saints, in their experience of union with God, reach such profound "knowledge" of the divine mysteries, in which love and knowledge are fused, that they are of help to theologians themselves in their task of study, of "intelligentia fidei," of "intelligentia" of the mysteries of the faith, of real deepening in the mysteries, for example, of what purgatory is.
