How does the shifting point of view in Heart of Darkness help the reader discover the narrator's psychological being?

I think that it is deliberate on Conrad's part to not give
us a point of view where psychological totality is present. In my mind, one of Conrad's
fundamental points in his novel is the danger that lurks with a totalizing vision of
absolutism, and the terror it can impose.  Kurtz and European "enlightenment" were seen
in this totalizing light and the result was disastrous for both the indigenous people of
the Congo and for Kurtz, himself.  Conrad avoids this same trap with presenting a point
of view framework that consists of many voices, and not one becoming a source of
totality. There is Marlow, whose voice is most dominant.  There is also the narrator who
opens the story, and who allows Marlow's voice to become evident.  There is also Conrad,
himself, who brings all of these voices to the forefront. In the end, there is no
singular narrator, no force of totality.  Rather, there are multiple voices and there is
a level of incompleteness in all of them, leaving it up to the reader to assess in their
own mind which is most reliable.  In constructing his narrative in this manner, Conrad
has been able to accomplish a significant achievement in both style and
theme.