Umberto Eco:

In spite of some fuzziness regarding the difference between various historical forms of fascism, I think it is possible to outline a list of features that are typical of what I would like to call Ur-Fascism, or Eternal Fascism. These features cannot be organized into a system; many of them contradict each other, and are also typical of other kinds of despotism or fanaticism. But it is enough that one of them be present to allow fascism to coagulate around it.

this cited in essay on liberal fascism by subcommandante marcos