A man was meant to be doubtful about himself, but undoubting about the truth; this has been reversed. Nowadays the part of a man that a man does assert is exactly the part he ought not to assert - himself. The part he doubts is exactly the part he ought not to doubt - the Divine Reason.
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.
There is nothing makes a man suspect much, more than to know little, and therefore men should remedy suspicion by procuring to know more, and not keep their suspicions in smother.
Doubt, indulged and cherished, is in danger of becoming denial; but if honest, and bent on thorough investigation, it may soon lead to full establishment of the truth.
Suspicions that the mind, of itself, gathers, are but buzzes; but suspicions that are artificially nourished and put into men's heads by the tales and whisperings of others, have stings.