CathInfo.com

I wish to share some thoughts on psychology which I have learned from approved, traditional Catholic sources. 

According to Thomistic psychology, a saint would never have a true mental illness, and this is because a saint knows how to perfectly receive the crosses that God sends us. That is not to say that a saint cannot feel the rebellion of the passions or experience evil thoughts, which is common with everyone who has original sin; the essence of mental illness as St. Thomas teaches it, is to have a real disorder in the intellect and will, arising from dwelling on the wrong thoughts deliberately, and making poor decisions with our will. Who does not know that dwelling excessively on sad things causes depression, for instance? The modern medical system seems to think that the mere experience of evil thoughts and feelings, is what mental illness consists of. How unfortunate are the results of this mindset, which we are witnessing today with children being medicated, when it is totally unnecessary.

Our Lady did not suffer from PTSD, for example, after witnessing her beloved Son being brutally murdered in front of her eyes, and drained of the last drop of His blood. Objectively, that was extremely traumatic. However, Our Blessed Mother was not traumatized, since she was perfectly resigned to the holy will of the Eternal Father, and remained at peace in the depths of her heart, despite the extreme agony of soul she endured. This is what earned her the title of "Queen of Martyrs", and this is why we see in the martyrs of the Church this supernatural bravery and heavenly fortitude, in the face of what we would call trauma. 

An example of this is in the heroic words of St. Ignatius of Antioch, expressing his desire for martyrdom: 

“Suffer me to be the food of wild beasts, whereby I may attain unto God. I am the wheat of God, and am to be ground by the teeth of wild beasts, in order that I may be found the pure bread of Christ…" 
— From an account of the martyrdom of St. Ignatius of Antioch, given in “The Victories of the Martyrs”, by St. Alphonsus Liguori.

In essence, St. Thomas's teaching is that virtue heals the soul, which in turn heals the body, since both are connected. This is accomplished by the grace of God, the God Who is also the author of our human nature. He can heal us in soul and in body. Our Lord revealed to St. Gertrude the Great that sometimes He permits defects to remain in us in order to try our patience and make us grow in humility, so some people may retain the remnants of disorder that arose from their traumatic experiences for that reason, despite their best efforts.

Fr. Raymond, O.P. in "The Spiritual Director and Physician" book referenced in this thread, also speaks of the concept that virtue heals, and that the essential cause of all mental illness, is rejection of the cross. I am sure we all know from experience, that the more we let ourselves lose our peace and self-control through impatience, the more we lose control of our thoughts, words, and sometimes actions, which is truly what mental illness consists of. 

Our Lord said: "In your patience you shall possess your souls." — Luke 21:19.

According to Thomistic psychology, a saint would never have a true mental illness, and this is because a saint knows how to perfectly receive the crosses that God sends us. That is not to say that a saint cannot feel the rebellion of the passions or experience evil thoughts, which is common with everyone who has original sin; the essence of mental illness as St. Thomas teaches it, is to have a real disorder in the intellect and will, arising from dwelling on the wrong thoughts deliberately, and making poor decisions with our will. Who does not know that dwelling excessively on sad things causes depression, for instance? The modern medical system seems to think that the mere experience of evil thoughts and feelings, is what mental illness consists of. How unfortunate are the results of this mindset, which we are witnessing today with children being medicated, when it is totally unnecessary. remnants of disorder that arose from their traumatic experiences for that reason, despite their best efforts.

I know Aquinas wouldn't have been aware of this (he might have called it "humors" or something like that), but what about people who have a chemical imbalance in their brain?  Are they shut off from sainthood because of something over which they have no control?