The two most celebrated novels about European colonialism in Africa were written, appropriately enough, by a European, Joseph Conrad (Heart of Darkness, 1902), and by an African, Chinua Achebe (Things Fall Apart, 1958). These writers were both witness to traumatic change in Africa, they travelled extensively and, to some extent, were displaced figures, Conrad as a Ukrainian-Pole in England, and Achebe as an Igbo in a Hausa- and Yoruba-dominated Nigeria and then, later, as a Nigerian in America, where he still lives. There the similarities end. In a lecture delivered in 1975, Achebe denounced Conrad as an unadulterated “racist”. Heart of Darkness, he said, “projects the image of Africa as the ‘other world’, the antithesis of Europe and therefore of civilisation, a place where man’s vaunted intelligence and refinement are finally mocked by triumphant bestiality”.

Achebe is an insistently moral reader, and his reading of Conrad - as orientalist and European supremacist - influenced a whole generation of students of post-colonial literature. In Achebe’s vision of what constitutes literary art, the ethical and the aesthetic are inseparable. The aesthetic is an expression of the ethical. No work expressive of racism can be considered a work of art. Conrad, he says, in an awkward phrase, “eliminates the African as human factor”. He continues: “Africa as a metaphysical battlefield devoid of all recognisable humanity, into which the wandering European enters at his peril. Can nobody see the preposterous and perverse arrogance in thus reducing Africa to the role of props for the break-up of one petty European mind? But that is not even the point. The real question is the dehumanisation of Africa and Africans which this age-long attitude has fostered and continues to foster in the world. And the question is whether a novel which celebrates this dehumanisation, which depersonalises a portion of the human race, can be called a great work of art.”

The narrator of Heart of Darkness is a young English sailor called Marlow. He has returned to London from his travels in central Africa with a remarkable story to tell - of the rapacity and venality of the Belgian exploitation of the Congo and the subjugation of the local peoples there, and of the moral and psychological disintegration of Kurtz, a once idealistic high-bourgeois European intellectual who, in despair and embracing nihilism, withdrew to a remote trading post on the Congo River to become the debauched head of his own cannibal kingdom.

Marlow is, at all times, a deeply unreliable narrator, at one moment sympathetic to and at another contemptuous of the colonial project: “The conquest of the earth, which mostly means the taking it away from those who have a different complexion or slightly flatter noses than ourselves, is not a pretty thing when you look into it too much.”

The story he tells of Africa is necessarily partial, circumscribed by the old racial and class hierarchies: it is Marlow, not Kurtz, who speaks repeatedly of the heart of darkness and of the irrationality and metaphysical horror of Africa. It is Marlow who portrays the black Africans he encounters in a pejorative and monolithic way. “A quarrelsome band of footsore sulky niggers trod on the heels of the donkey,” he writes early in the book, establishing an idiom. It could be Ron Atkinson speaking.

We are told by Marlow that Kurtz’s gift, before his turn towards barbarism, was language: “his ability to talk, his words - the gift of expression, the bewildering, the illuminating, the most exalted and the most contemptible, the pulsating stream of light, or the deceitful flow from the heart of an impenetrable darkness”. We have to take his word on this, because we hear little from Kurtz himself and read none of his supposedly elegant prose. And the miraculous gift of expression is never extended to the Africans in the book: they can speak all right, but they are never articulate or coherent.

The effects are similar in Louis-Ferdinand Celine’s astounding Journey to the End of the Night (1932), perhaps the greatest work of literary nihilism, and one of the finest novels of the past century, a novel even more problematic than Heart of Darkness in what it reveals of educated European colonial attitudes to Africa. The narrator of the novel is a French doctor called Ferdinand Bardamu. He is scabrous, cynical, enraged, yet often very witty. He is the precursor of Michel Houellebecq’s dissolute and fatigued last men. His story is told in an urgent vernacular, a hybrid of the lyric and the gutter. The engine of his disgust is an irrational misanthropy. Wounded on the Western Front, Ferdinand travels to what is now Cameroon in search of a new start. He has none of Marlow’s youthful wonder. He knows where he is going and what he will find there: “We were heading for Africa, the real, grandiose Africa of impenetrable forests; fetid swamps, inviolate wildernesses, where black tyrants wallowed in sloth and cruelty on the banks of never-ending rivers.”

If Kurtz is an enlightenment rationalist exhausted and then destroyed by his experience of Africa, Ferdinand is representative of the post-Christian new man who emerged from the trenches of the Western Front, the grand renunciator who believes in nothing, least of all in the possibility of progress. He survives his African experience - “Whole trees bristling with live clamour mutilated erections, horror” - precisely because, unlike Kurtz and indeed Marlow, he has no ideals to lose: the chaos and disorder of Africa merely affirm his own nihilism.

There are close similarities, in subject and theme, between these novels and Georges Simenon’s Tropic Moon (1933), which has just been reissued by the publishing arm of the New York Review of Books and deserves to find a wide readership. Tropic Moon (Le Coup de lune) is set during the Thirties in francophone Gabon. Joseph Timar, from La Rochelle, is the nephew of an influential government official, and he arrives in Libreville to take up a job at a trading post deep in the bush. You sense that he has lost his way back home and Africa offers him the possibility of adventure, another chance. He takes a room at a hotel, and soon begins an affair with Adele, the wife of the hotelier. In fact, it is less an affair than a series of random sexual encounters; Timar learns, quickly, that most of the white men who hang around the hotel’s bar have slept with the bored Adele, who wears nothing beneath her transparent dresses.

Then, over the course of a couple of nights, Adele’s husband dies and a black servant is murdered. It becomes appar- ent to Timar that everyone in the white settler community knows that Adele is responsible for the murder; but he is sick with desire for her and, rather than investigate, intensifies his affair. Together he and Adele set off upriver for the remote timber camp.

Great claims have been made for Simenon (1903-89), most recently by the political philosopher John Gray and the novelist John Banville. In truth, he is a limited artist, but an interesting one. He has a robust, even unbreakable style: his brusque sentences are stripped of all superfluous ornamentation, the vocabulary is reduced, there is little description of landscape or place, and he follows his characters less in thought than in action.

Simenon was grotesquely prolific, writing more than 400 books, the most popular of which are the genre thrillers featuring the detective Maigret. His more contemplative books are what he called his romans durs - the hard books. And the best of these are Tropic Moon and Monsieur Monde Vanishes, which is about an apparently settled middle-class Parisian family man who one day, without warning, walks out on his wife and loses him-self in the floating world of the Riviera, where he seeks to live authentically among whores, adventurers and criminals.

“I was always tempted by what I call complete liberty,” Simenon once said, and many of his characters, in the romans durs, are seeking release from domestic obligation and mundane routine, through sex, travel or crime. But they invariably discover that there is no such thing as complete liberty: other people, with their conflicting needs, as well as the rule of law, serve as brakes on our more treacherous desires.

When Timar arrives in Gabon he has a young man’s optimism, but soon, like the other settlers, he is listless. The tropical heat oppresses him. The days are long and heavy. His head is often “thick with drink before lunch”. The “blacks” out on the streets of Libreville or in the bush move as one: homogenous, indistinguishable, nameless, without identity.

Simenon, who travelled through French West Africa, was a determined critic of colonialism, and Tropic Moon is a more subtle book, in many ways, than Heart of Darkness, though just as despairing. Its subtlety lies in what happens to Timar late in the book: travelling by canoe downriver from the timber camp (Adele has fled the camp and is presumed to be back in Libreville), he finds himself unexpectedly moved by the solidarity of the African oarsmen, the harmony of their collective endeavour. He watches them in a rapture of mutuality. “Twelve paddles rose out of the water together, dripping liquid pearls in the sunlight. They hung suspended for a moment and then came down, while the men lifted their voices in a sad unchanging chant whose muted powerful rhythm would be with them throughout the trip.”

Timar begins to see that the Africans are less an undifferentiated mass - “the blacks” - than sovereign selves, with needs and longings similar to his own. As this is Simenon, things are further complicated by sex. Resting in a remote village on the way back to Libreville, Timar meets a young “native” woman. She is an orientalist’s fantasy: “She was naked except for a bunch of dried grass that covered her sex. Timar had never seen breasts like hers before . . .” Later, she visits the hut where he is to spend the night. Simenon closes the door on what happens next, but a sense of mutual erotic need is established in a few terse paragraphs. Timar is changed further by the experience and, on his arrival in Libreville, he refuses to be complicit in an attempt by Adele to evade arrest for the murder of the servant through framing an innocent man, the obligatory local black. Timar desires Adele intensely, feels a kind of inchoate love for her, and she for him, but he also loathes the corruption and injustice of the whole rotten French-administered set-up in Gabon, and he must act to prevent injustice.

In Things Fall Apart, Okonkwo, the proud Igbo leader from the village of Umuofia who rebels against the arrival of missionaries and British bureaucrats in his ancestral village, hangs himself from a tree, in one last act of defiance and despair. It is as if he knows what awaits his people and continent, and he cannot bear it. In Journey to the End of the Night, Ferdinand leaves Africa as he found it - in a fury of exasperation and contempt. In Heart of Darkness, Kurtz, sick and withered at the end of his life, crawls alone into the bush. “I am lying here waiting for death,” he tells Marlow. The man who once had “immense plans” has lived too long and seen too much. His conclusion? “Exterminate all the brutes.”

As for the Africa-returned Marlow, once more settled in London, he tells his aunt, who is worrying about his health, that it is not “my strength that needed nursing, it was my imagination that wanted soothing”. And, in Tropic Moon, Timar eventually leaves Africa, fever-stricken and defeated, without hope or aspiration. He, like Marlow, cannot even begin to imag-ine what is happening in the land he left behind. “Africa doesn’t exist,” he mutters to himself, at the very end of the book. “Africa - it doesn’t exist. Africa . . .”

What each of these writers seems to be saying in his own way is that the European has no place in Africa: the cultural misunderstanding is too profound, the history too painful, the bitterness too great.

“Tropic Moon is a dark masterpiece,” John Banville wrote recently in the Guardian, “darker even than Heart of Darkness.” That a stylist as fastidious as the Booker-garlanded Banville should use an adjective so complacent when commenting on a novel set in Africa is merely further confirmation of Achebe’s pessimism. So must Conrad always remain our first point of reference when considering representations of Africa in the novel? Of course not, because, in the end, the best stories, memoirs and essays about Africa - the truest and most empathetic - are written by Africans, from an African perspective, if not necessarily for an African readership.

For one thing, their imaginations do not need soothing and their vision of the continent does not, as it does for Timar in Tropic Moon, end with an ellipsis . . . beyond which there is only horror, horror.