If the novel's 'heart of darkness' is largely concerned with imperialism and the exploitation of 'those who have a different complexion or slightly flatter noses than ourselves,' Conrad's story, with its River Thames setting, ends on an unmistakable note of complicity.
Situated on the Thames, London was Britain’s major port, and the city played a central role in the transatlantic trade in enslaved peoples from West Africa to the Americas during and after the reign of Elizabeth I. Ships owned by London merchants dominated the slave trade during the 17th and early 18th centuries.
Etymologically, there is another link between the River Thames and darkness. The river’s name is thought to derive from the Middle English Temese, which originated from the Celtic, Tamesas. Along with the Irish teinheal and Welsh tywyll (both meaning darkness), the word is believed to originate from the Proto-Celtic temeslos, meaning dark water. This word, probably Proto-Indo-European in origin, is considered a cognate of the Sanskrit word for darkness, tamas – in classical Indian philosophy a word with highly negative connotations, with some relevance to the thematic concerns of Heart of Darkness.