The Holy Spirit Himself has judged it useful to reveal these terrible crosses to all in the incomparable book of Job. These alone enable us to comprehend the scenes of certain exclamations of Our Lord on Calvary. From such crosses we also learn what kind of sufferings await us in purgatory.
The purpose of these crosses is not so much to spiritualize our sensibility, as to supernaturalize our spirit. These crosses serve to detach the spirit from itself and to subject it to God in such a way that it is transformed, so to speak, into Him in the same way that wood, becoming a prey to the fire, warms and illumines like the fire (St. John of the Cross). These crosses of the spirit, send directly by God, make the superior part of the soul suffer. The means God uses to purify us is a supernatural light, so living and so intense that the eyes of the soul, still not strong enough to bear it, are dazzled and blinded by it, experiencing an acute suffering from it, has happened to the owl that is dazzled and blinded by too much sunlight.
But this mysterious divine light, though it is blinding, makes one see. First of all it makes the soul see what it is in reality, showing it the unsuspected depths of its misery. Then, in contrast, it reveals God in His transcendence and infinite purity. This revelation is in a manner so entirely new, though very obscure, that the soul seems bedazzled, no longer seeing the relationship between this knowledge and that which it formerly enjoyed. Although it is elevated by its labors toward the light, it seems to the person that it is more and more engulfed by the night.
Now we shall see how Our Lord purifies, in this painful ascent, the humility of the saints, their faith, their hope, and their charity, that is, the virtues proper to the higher degrees of the soul and spirit. In this way we shall discover how superficial and imperfect our humility, faith, hope, and charity still are. . ." pg. 134, 135 KNOWING THE LOVE OF GOD by Fr. Reginald Garrigou-Lagrange, O.P.