A classic quote from R.D. Laing of anti-psychiatry fame:
I am very interested in words, and what we have words for and what we haven’t got words for. For instance, the word “paranoia.” It always seems very strange to me that we have this word which means, in effect, that someone feels that he is being persecuted when the people who are persecuting him don’t think that he is. But we haven’t got a word for the condition in which you are persecuting someone without realizing it, which I would have thought is as serious a condition as the other, and certainly no less common.