I came across this recently, but honestly I forget where (sorry for the consequent linkopenia!).
This comes from a 1963 speech by left-winger Richard Hofstadter, and was directed against the paranoids of the American “right” at the time: the anti-communists, the McCarthyites, etc. In its analysis of the paranoid mind, it appears more applicable (in my opinion, at any rate) to the current Left. Part of the appeal of his analysis I think is that both sides of the present ideological divide will think it accurately describes The Enemy.
Of course, my side is right.
Heh

