But when you first embark on the Path, your awareness won't be focused. You're likely to see all sorts of strange, dreamlike scenes. But you shouldn't doubt that all such scenes come from your own mind and nowhere else.
In dealing with the arrogant asserter of doubt, it is not the right method to tell him to stop doubting. It is rather the right method to tell him to go on doubting, to doubt a little more, to doubt every day newer and wilder things in the universe, until at last, by some strange enlightenment, he may begin to doubt himself.