Further, she describes the soul in sin as "rooted in a pool of pitch-black, evil smelling water, it produces nothing but misery and filth."
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In a dialogue between Captain Picard and Armus; Picard quotes Percy Bysshe Shelly from "Prometheus Unbound"...
"All spirits are enslaved that serve things evil."
Armus: "You do not understand. I do not serve things evil; I am evil."
Captain Picard: "Oh, no. You're not."
Armus: I am a skin of evil, left here by a race of Titans, who believed if they rid themselves of me, they would free the bonds of destructiveness.
Back to the Interior Castle, St. Teresa goes onto say; "I know of a person to whom Our Lord wished to show what a soul was like when it committed mortal sin.That person says that, if people could understand this, she thinks they would find it impossible to sin at all..." That person she is referring to is Teresa, herself.
In our fallen world we are all subject to sin and this vile, blackness that can coat our soul. To me that imagery is revolting that are souls can look like Armus. In our world, we have a savior that can free ourselves from the bonds of evil. That savior is Jesus Christ. We need the cleansing, pure water of grace that can clear off the muck and slime from our souls. Pray, Brothers and Sisters that in St. Teresa's words that "surely if you understand your own natures, it is impossible that you will not strive to remove the pitch which darkens the the crystal of your soul."
I am scrubbing as we speak...