Black Narcissus and Repression
There is a comparison to be made between the characters in this film and the three elements of Freud's psychic apparatus: The super-ego, the ego and the id. Freud defines the super-ego as the regulatory force, the moral backbone and idealized version of ourselves that we will work to protect. The id on the other hand, is our subconscious instinctual mind. The ego's job is to work to live within the super-ego's confines, sublimate the id and all the while deal with the real world and the complexities therein.
Only seen briefly in the film, the Mother Superior can easily be seen as Clodagh's super-ego. It can be summed up simply in this quote, in a discussion about how to deal with Sister Ruth, who the Mother Superior has instructed Clodagh to give tasks that will make her feel important. Sister Clodagh asks if it is a good idea for Ruth to feel important, and the Mother Superior responds: "Spare her some of your own importance - if you can." Acting as super-ego, she reprimands Sister Clodagh for being prideful. While the scene is brief, it perfectly sets up the character of Clodagh as not truly living up to the asceticism that she believes she needs.
Clodagh's ego, is Clodagh herself, constantly trying to reconcile her repressed desires, memories, etcetera with her super-ego's expectations of purity and perfection. Not only does the internal conflict raging inside of her make her situation precarious, the hostile environment she has been thrust in to only seem to represent her struggle further. We see in the young general her past, the lust and inequality of power and commitment. A powerful man who takes what he wants from a woman, then leaves her, as Con did, leaving for America for his "true future".
Descending in to her id, we find Sister Ruth. Through the film we see her degenerate rapidly, becoming more animalistic and emotional, being over stimulated by the isolation and...