What Is Questioning Doubt?

All unresolved questions can become a questioning doubt; the only difference lies in whether it is deep or shallow, and whether it can be sustained. There is also the matter of where the doubt arises. If the doubt is raised merely by the mind consciousness, it is very shallow—it can be forgotten in a moment and will not be pursued to the end; it is almost always intermittent, and it is very difficult to truly resolve the problem. Only when the manas deep within the mind raises the doubt can one pursue it day and night without cease, doubting that question whether walking, standing, sitting, or lying down, with the thought never interrupted, until the question is resolved.