Heart of Darkness is all about the ironic falseness of any notion of "civilized."  In the name of civilization, Kurtz goes into Africa ostensibly to bring light to darkness but--in fact and from the outset--to bring out the white (light) ivory to the dark moving Thames.  The "savages" are unclear because we never do and can never can know how they acted before Kurtz came, but whatever it was, however violent or cruel, we have no reason to think it was about being "civilized" in any Western sense.  So the book is about hypocrisy and brutality and self-deception on the part of white Europe.  This is hardly even interpretation: Conrad's symbolism is very overt and explicit, as when he shows a dying African with a white thread around his neck or when Marlow realizes how he too could be drawn into the emotion of the scene when he follows Kurtz into a ritual or when he shows the heads on poles around Kurtz's compound--and especially when he lies to Kurtz's Intended, thereby upholding what he knows is not true while always recalling and contemplating "The Horror! The Horror."
 
But Eliot would have seen this as savage.  He was very interested in and used imagery of what he considered "savage," and the dominant psychology of the day assumed a "primitive" and a "civilized" human development.  Vittoz, who treated Eliot, even claimed there were two brains, the primitive and the civilized, and that neurasthenia (Eliot's diagnosis) occured when the civilized brain lost control of the primitive brain.  The solution was those exercises in regaining control through concentration.  Compare, for example, the way Mr. Hyde is called ape-like, and the assumptions of criminal "types," as in Lombroso:
 
HE [Lombroso] BEGAN WITH THE BASIC ASSUMPTION OF THE BIOLOGICAL NATURE OF HUMAN CHARACTER AND BEHAVIOR:

These ideas permeated all kinds of disciplines, and Eliot not only was familiar with them but chose a psychologist who wrote a book defining them.

Nancy