As for the vice of lust - aside from what it means for spiritual persons to fall into this vice, since my intent is to treat of the imperfections that have to be purged by means of the dark night - spiritual persons have numerous imperfections, many of which can be called spiritual lust, not because the lust is spiritual but because it proceeds from spiritual things. It happens frequently that in a person's spiritual exercises themselves, without the person being able to avoid it, impure movements will be experienced in the sensory part of the soul, and even sometimes when the spirit is deep in prayer or when receiving the sacraments of Penance or the Eucharist. These impure feelings arise from any of three causes outside one's control. First, they often proceed from the pleasure human nature finds in spiritual exercises. Since both the spiritual and the sensory part of the soul receive gratification from that refreshment, each part experiences delight according to its own nature and properties. The spirit, the superior part of the soul, experiences renewal and satisfaction in God; and the sense, the lower part, feels sensory gratification and delight because it is ignorant of how to get anything else, and hence takes whatever is nearest, which is the impure sensory satisfaction. It may happen that while a soul is with God in deep spiritual prayer, it will conversely passively experience sensual rebellions, movements, and acts in the senses, not without its own great displeasure. This frequently happens at the time of Communion. Since the soul receives joy and gladness in this act of love - for the Lord grants the grace and gives himself for this reason - the sensory part also takes its share, as we said, according to its mode. Since, after all, these two parts form one individual, each one usually shares according to its mode in what the other receives. As the Philosopher says: Whatever is received, is received according to the mode of the receiver. Because in the initial stages of the spiritual life, and even more advanced ones, the sensory part of the soul is imperfect, God's spirit is frequently received in this sensory part with this same imperfection. Once the sensory part is reformed through the purgation of the dark night, it no longer has these infirmities. Then the spiritual part of the soul, rather than the sensory part, receives God's Spirit, and the soul thus receives everything according to the mode of the Spirit.
With the veil removed by the rending of Jesus' flesh, with nothing on God's side to prevent us from entering, why do we tarry without? Why do we consent to abide all our days just outside the Holy of Holies and never enter at all to look upon God? We hear the Bridegroom say, `Let me see thy countenance, let me hear thy voice; for sweet is thy voice and thy countenance is comely.' (Song of Sol 2:14) We sense that the call is for us, but still we fail to draw near, and the years pass and we grow old and tired in the outer courts of the tabernacle. What doth hinder us?The answer usually given, simply that we are `cold,' will not explain all the facts. There is something more serious than coldness of heart, something that may be back of that coldness and be the cause of its existence. What is it? What but the presence of a veil in out hearts? A veil not taken away as the first veil was, but which remains there still shutting out the light and hiding the face of God from us. It is the veil of our fleshly fallen nature living on, unjudged within us, uncrucified and unrepudiated. It is the close- woven veil of the self-life which we have never truly acknowledged, of which we have been secretly ashamed, and which for these reasons we have never brought to the judgment of the cross. It is not too mysterious, this opaque veil, nor is it hard to identify. We have but to look in our own hearts and we shall see it there, sewn and patched and repaired it may be, but there nevertheless, an enemy to our lives and an effective block to our spiritual progress.This veil is not a beautiful thing and it is not a thing about which we commonly care to talk, but I am addressing the thirsting souls who are determined to follow God, and I know they will not turn back because the way leads temporarily through the blackened hills. The urge of God within them will assure their continuing the pursuit. They will face the facts however unpleasant and endure the cross for the joy set before them. So I am bold to mane the threads out of which this inner veil is woven. It is woven of the fine threads of the self-life, the hyphenated sins of the human spirit. They are not something we do, they are something we are, and therein lies both their subtlety and their power.