Insanity (mental illness) is not so much an "illness" as a desperate and oxymoronical state of being. The "insane" long to be left alone to immerse themselves in hopelessness and pain and slowly destroy themselves. The insane crave love, kindness, and companionship as a way to climb out of themselves and find purpose in helping others. The insane live in a fantastical world of unparalleled loveliness and are extremely grateful for the smallest display of beauty or act of charity. The insane live in a phantasmagorical world of unimaginable terror and ugliness and are personally offended by the minutest display of evil or selfish act. They wish to sacrifice their will completely to any Deity or man, actual or fabricated, in an act of pure love. They seek to place their own well-being above all else and escape all influence of the world, even themselves, and in the process of doing so, they retreat so deeply into themselves as to become the most egocentric creature possible.
With all of their opposing actions and philosophies, they manage to tear themselves into two or more distinct personalities at war with each other, resulting in the inescapable turmoil of their souls. There is a terrible beauty in this inner conflict of Good and Evil. It is a battle that shall not cease until the death of the individual fighting it, and the chances of either side prevailing are bleak.
Then there are the well-intentioned people who try to help these miserable individuals win their wars. They study the minds of these individuals, observe the conflict, and formulate theories to answer all the why's and how's of the matter. They turn to psychology and psychiatry for the analysis of these answers, and to chemistry and physiology for the pill or therapy that will miraculously end the internal conflict. They are always taking part in the futile search for the cure. Hopefully, one day, they will find it and allow the insane to attain victory, though no one, except themselves, believes that they actually stand any chance of success.