At a dinner party she meets X, whom she has not seen in years. Is he still teaching at the University of Queensland, she asks? No, he replies, he has retired and now works the cruise ships, travelling the world, screening old movies, talking about Bergman and Fellini to retired people. He has never regretted the move. 'The pay is good, you get to see the world, and – do you know what? – people that age actually listen to what you have to say.' He urges her to give it a try: 'You are a prominent figure, a well-known writer. The cruise line I work for will jump at the opportunity to take you on. You will be a feather in their cap. Say but the word and I'll bring it up with my friend the director.'

The proposal interests her. She was last on a ship in 1963, when she came home from England, from the mother country. Soon after that they began to retire the great ocean-going liners, one by one, and scrap them. The end of an era. She would not mind doing it again, going to sea. She would like to call at Easter Island and St Helena, where Napoleon languished. She would like to visit Antarctica – not just to see with her own eyes those vast horizons, that barren waste, but to set foot on the seventh and last continent, feel what it is like to be a living, breathing creature in spaces of inhuman cold.

X is as good as his word. From the headquarters of Scandia Lines in Stockholm comes a fax. In December the SS Northern Lights will be sailing from Christchurch on a fifteen-day cruise to the Ross Ice Shelf, and thence onward to Cape Town. Might she be interested in joining the education and entertainment staff? Passengers on Scandia 's cruise ships are, as the letter puts it,'discriminating persons who take their leisure seriously'. The emphasis of the on-board programme will be on ornithology and cold-water ecology, but Scandia would be delighted if the noted writer Elizabeth Costello could find the time to offer a short course on, say, the contemporary novel. In return for which, and for making herself accessible to passengers, she will be offered an A-class berth, all expenses paid, with air connections to Christchurch and from Cape Town, and a substantial honorarium to boot.

It is an offer she cannot refuse. On the morning of 10 December she joins the ship in Christchurch harbour. Her cabin, she finds, is small but otherwise quite satisfactory; the young man who coordinates the entertainment and self-development programme is respectful; the passengers at her table at lunchtime, in the main retired people, people of her own generation, are pleasant and unostentatious.

On the list of her co-lecturers there is only one name she recognizes: Emmanuel Egudu, a writer from Nigeria. Their acquaintance goes back more years than she cares to remember, to a PEN conference in Kuala Lumpur. Egudu had been loud and fiery then, political; her first impression was that he was a poseur. Reading him later on, she had not changed her mind. But a poseur, she now wonders: what is that? Someone who seems to be what he is not? Which of us is what he seems to be, she seems to be? And anyway, in Africa things may be different. In Africa what one takes to be posing, what one takes to be boasting, may just be manliness. Who is she to say?

Towards men, including Egudu, she has, she notices, mellowed as she has grown older. Curious, because in other respects she has become more (she chooses the word carefully) acidulous.

She runs into Egudu at the captain's cocktail party (he has come aboard late). He is wearing a vivid green dashiki, suave Italian shoes; his beard is spotted with grey, but he is still a fine figure of a man. He gives her a huge smile, enfolds her in an embrace. ' Elizabeth!' he exclaims. 'How good to see you! I had no idea! We have so much catching up to do!'

In his lexicon, it appears, catching up means talking about his own activities. He no longer spends much time in his home country, he informs her. He has become, as he puts it, 'an habitual exile, like an habitual criminal'. He has acquired American papers; he makes his living on the lecture circuit, a circuit that would appear to have expanded to encompass the cruise ships. This will be his third trip on the Northern Lights. Very restful, he finds it; very relaxing. Who would have guessed, he says, that a country boy from Africa would end up like this, in the lap of luxury? And he treats her again to his big smile, the special one.

I'm a country girl myself, she would like to say, but does not, though it is true, in part. Nothing exceptional about being from the country.

Each of the entertainment staff is expected to give a short public talk. 'Just to say who you are, where you come from,' explains the young coordinator in carefully idiomatic English. His name is Mikael; he is handsome in his tall, blond, Swedish way, but dour, too dour for her taste.

Her talk is advertised as 'The Future of the Novel', Egudu's as 'The Novel in Africa '. She is scheduled to speak on the morning of their first day out to sea; he will speak the same afternoon. In the evening comes 'The Lives of Whales', with sound recordings.

Mikael himself does the introduction. 'The famous Australian writer,' he calls her, 'author of The House on Eccles Street and many other novels, whom we are truly privileged to have in our midst.' It vexes her to be billed once again as the author of a book from so far in the past, but there is nothing to be done about that.

'The Future of the Novel' is a talk she has given before, in fact many times before, expanded or contracted depending on the occasion. No doubt there are expanded and contracted versions of the novel in Africa and the lives of whales too. For the present occasion she has chosen the contracted version.

'The future of the novel is not a subject I am much interested in,' she begins, trying to give her auditors a jolt. 'In fact the future in general does not much interest me. What is the future, after all, but a structure of hopes and expectations? Its residence is in the mind; it has no reality.

'Of course, you might reply that the past is likewise a fiction. The past is history, and what is history but a story made of air that we tell ourselves? Nevertheless, there is something miraculous about the past that the future lacks. What is miraculous about the past is that we have succeeded – God knows how – in making thousands and millions of individual fictions, fictions created by individual human beings, lock well enough into one another to give us what looks like a common past, a shared story.

'The future is different. We do not possess a shared story of the future. The creation of the past seems to exhaust our collective creative energies. Compared with our fiction of the past, our fiction of the future is a sketchy, bloodless affair, as visions of heaven tend to be. Of heaven and even of hell.'

The novel, the traditional novel, she goes on to say, is an attempt to understand human fate one case at a time, to understand how it comes about that some fellow being, having started at point A and having undergone experiences  and  and D, ends up at point Z. Like history, the novel is thus an exercise in making the past coherent. Like history, it explores the respective contributions of character and circumstance to forming the present. By doing so, the novel suggests how we may explore the power of the present to produce the future. That is why we have this thing, this institution, this medium called the novel.

She is not sure, as she listens to her own voice, whether she believes any longer in what she is saying. Ideas like these must have had some grip on her when years ago she wrote them down, but after so many repetitions they have taken on a worn, unconvincing air. On the other hand, she no longer believes very strongly in belief. Things can be true, she now thinks, even if one does not believe in them, and conversely. Belief may be no more, in the end, than a source of energy, like a battery which one clips into an idea to make it run. As happens when one writes: believing whatever has to be believed in order to get the job done.

If she has trouble believing in her argument, she has even greater trouble in preventing that absence of conviction from emerging in her voice. Despite the fact that she is the noted author of, as Mikael says, The House on Eccles Street and other books, despite the fact that her audience is by and large of her generation and ought therefore to share with her a common past, the applause at the end lacks enthusiasm.

For Emmanuel's talk she sits inconspicuously in the back row. They have in the meantime had a good lunch; they are sailing south on what are still placid seas; there is every chance that some of the good folk in the audience – numbering, she would guess, about fifty – are going to nod off. In fact, who knows, she might nod off herself; in which case it would be best to do so unnoticed.

'You will be wondering why I have chosen as my topic the novel in Africa,' Emmanuel begins, in his effortlessly booming voice. 'What is so special about the novel in Africa? What makes it different, different enough to demand our attention today?

'Well, let us see. We all know, to begin with, that the alphabet, the idea of the alphabet, did not grow up in Africa. Many things grew up in Africa, more than you might think, but not the alphabet. The alphabet had to be brought in, first by Arabs, then again by Westerners. In Africa writing itself, to say nothing of novel-writing, is a recent affair.

'Is the novel possible without novel-writing, you may ask? Did we in Africa have a novel before our friends the colonizers appeared on our doorstep? For the time being, let me merely propose the question. Later I may return to it.

'A second remark: reading is not a typically African recreation. Music, yes; dancing, yes; eating, yes; talking, yes – lots of talking. But reading, no, and particularly not reading fat novels. Reading has always struck us Africans as a strangely solitary business. It makes us uneasy. When we Africans visit great European cities like Paris and London, we notice how people on trains take books out of their bags or their pockets and retreat into solitary worlds. Each time the book comes out it is like a sign held up. Leave me alone, I am reading, says the sign. What I am reading is more interesting than you could possibly be.

'Well, we are not like that in Africa. We do not like to cut ourselves off from other people and retreat into private worlds. Nor are we used to our neighbours retreating into private worlds. Africa is a continent where people share. Reading a book by yourself is not sharing. It is like eating alone or talking alone. It is not our way. We find it a bit crazy.'