The excerpt given below is taken from "The Spiritual Director and Physician" by Rev. Father V. Raymond, O.P., imprimatur 1914. The priest himself suffered from scruples, and is thus in a most fitting manner, suited to offer guidance and counsel to souls who suffer from the same malady. Unlike modern psychology and psychiatry that excludes the soul from treatment, Fr. Raymond discusses how all mental illnesses without exception, originates in some way or another, as an illness in the soul, particularly from a hatred, more or less, or suffering. He worked with the physicians of his day, as often in such cases, both the soul and body requires treatment. I found the following particularly revealing, since we have seen an unprecedented increase in mental illness in modern times. In the book, mental illness is referred to generally as neurosis.
The author sets out with a consideration on suffering, in some degree inevitable for all. Even here — if one knows how to read between the lines — it is clear that the writer understands perfectly the great moral cause of neurosis — namely, ignorance of the laws which govern human destiny. Parents are the first offenders in this respect, by making it a principle for themselves that they must spare the child even the slightest pain. The softness of modern training often stifles all individual initiative. Later on, in the school which knows little of God, the child is well instructed as to his rights, whilst his duties are lightly passed over. He is taught to use all means to attain to worldly happiness, and learns that all actions that conduce to this are truly good. A materialistic philosophy will teach him that man is all-sufficient for himself, and should look to no other guide than his reason. The result is that the youth of twenty is puffed out with pride like an inflated balloon that will not stand the slightest pricking. But he does not go far without encountering the prickings of deceptions and contradictions of every kind. The man whose will is not firmly set on the solid basis of faith will easily fall a victim to some form of neurosis, and all the more easily if he is already weakened, either by heredity or by the way in which he has been brought up.
From p.vi-vii: https://archive.org/details/SpiritualDirectorAndPhysician/page/n9/mode/2up?q=balloon