It is hard to avoid beginning with Conrad. In Heart of Darkness, Marlow's journey up the Congo conjures every sort of metaphor for quests and conquests, and the river has been famously transposed to other settings of colonial encounter. A certain timelessness attaches to the novel's associations of upriver isolation, loss of bearings, violence, and cultural dislocation. Simply raising the topic of rivers and their place in colonizing calls up surreal images of a slow ascent into a zone where all norms become distorted.

Assigning the novel such historical transcendence gives Conrad too much credit, of course. The romance with darkness and barbarity, and the portrayal of Africans as merely parts of an ominous natural landscape – these tropes are not universal but products of Conrad's century, and of Europe's bright ideas about its own civility. His version of the dangers and allure of passing into a psychological and physical state of no restraints seems also to depend on a purely secular and perhaps even republican understanding of sociability. Conrad was more concerned, after all, with Kurtz's abandonment of “the Intended” than with his spiritual malaise or betrayal of King Leopold, a figure well offstage throughout the novel. Kingship, for Kurtz, was very much beside the point.

A purely private betrayal would have mattered less three centuries before, just as madness itself would have been defined differently.