In light of a previous post on the subject it seems appropriate to attempt to clarify or expound further upon the issue raised therein. Where is the line that Rilke seems to be drawing between a doubt that is a worker in your life and the implied giving in to doubt that becomes skepticism?
Doubt is the natural outpouring of the soul when confronted with the pain of reality, not even the pain necessarily but simply reality itself. It’s simply wonder at what you do not know, or cannot know. More clearly, doubt is the experience of the soul.
The line between doubt and skepticism is one of questions. With one the questions find their origin in a wonder that has been disciplined; in the other the questions are asked incessantly without ever disciplining and tailoring them to your needs, to becoming useful. Discipline and questioning, this, it seems, is the line.