From "The Diary of the Rose", by Ursula K. LeGuin, 1976:
Allergy: A person can be exposed to pollen or bitten by fleas a thousand times without reaction. Then he gets a viral infection or a psychic trauma or a bee sting, and the next time he meets up with ragweed or a flea he begins to sneeze, cough, itch, weep, etc. It is the same with other irritants. One has to be sensitized.
"Why is there so much fear?" I wrote. Well now I know. Why is there no privacy? It is unfair and sordid. I cannot read the "classified" files kept in her office, though I work with the patients and she does not. But I am not allowed to have any "classified" material of my own. Only persons in authority can have secrets. Their secrets are all good, even when they are lies.