This is why Conrad builds such intense anticipation around Kurtz.

I saw my poleman give up the business suddenly, and stretch himself flat on the deck, without even taking the trouble to haul his pole in. He kept hold on it though, and it trailed in the water. At the same time the fireman, whom I could also see below me, sat down abruptly before his furnace and ducked his head....Sticks, little sticks, were flying about’7

It is not until a few lines later that Marlow conceptualises his perceptions, exclaiming ‘Arrows, by Jove!’8 Instances like this highlight how the perceptions of the subject are constituted by their preconceptions. In the above passage, for example, the phrases ‘give up the business’ and ‘without even taking the trouble to haul his pole in’ imply that Marlow assumes his crew are incompetent or lazy, when, as it later transpires, they are under attack. 

As Johnson comments, ‘it is vital to Conrad’s moral sense that he reveal again and again the value of this phenomenological perceiving...and...that he show his readers how perception usually depends on the preconceptions’9.

So what is this ‘moral sense’? In placing such emphasis upon the sensory impressions of his narrator, and in so doing highlighting the distinction between perception and cognition, Conrad inferred an epistemological relativism that anticipated much of the literature of the twentieth century. 

As Johnson notes, ‘In the awareness that there is no “realist” alternative to impressionism...Conrad had not jumped but dove head first into the twentieth century.’10 In turn, epistemological relativism implies a moral relativism, as individuals base decisions of conduct upon preconceived knowledge. Marlow’s narrative, as Watt argues, ‘aligns Heart of

Darkness with the subjective relativism of the impressionist attitude.’11 Did Conrad then deny the possibility of any secure moral position? At the very least, the novella expresses ‘doubt’, writes Caryl Phillips, ‘doubt about the supremacy of European humanity, and the ability of this supposed humanity to maintain its imagined status beyond the high streets of Europe.’12

Conrad’s clearest expression of this doubt in Heart of Darkness is through the character of Kurtz. He ascribes to Kurtz the philanthropic ideals of European civilization, with Marlow saying that ‘All Europe contributed to the making of Kurtz’13. 

We are told that he is ‘an emissary of pity, and science, and progress’14, and that he ‘had come out equipped with moral ideas of some sort’15. Yet, despite the constant references to Kurtz, for most of the novella he is notable only by his absence. 

Marlow concedes that ‘He was just a word for me. I did not see the man in the name any more than you do.’16 

The frequent references to Kurtz, coupled with the extended deferral of his eventual appearance, comprise the most significant use of delayed decoding in Heart of Darkness. The discrepancy between Marlow’s preconceptions of Kurtz and the reality of his appearance is the foundation upon which Conrad’s moral ambivalence lies.