There's never been any agreement, so far as I can tell, as to who it is we're supposed to be imagining the outside observer to be, and there are all sorts of conjectures.

这里的X到底是谁，就我所知，并没有定论,这个置身于外的观察者的身份仍然不明，关于这点又充满了各种各样的推测。

耶鲁公开课 - 弥尔顿课程节选