It must have cost him something to come out with it. Would have loved, past hypothetical. But just what did he mean? Conceivably he meant I would have loved to have painted you when you were still young, but I don't think so. I would have loved to have painted you when I was still a man: that is more like it. As he showed me the words I saw his lip quiver. I know one should not put too much store on trembling lips and watering eyes in old people, but still…

I smiled and tried to reassure him and took up my pose again, and he went back to his easel, and all was as before, except that I could see he was not painting any more, just standing there with the brush drying in his hand. So I thought – at last I come to the point – I thought, What the hell, and I loosened the wrap and shrugged it off my shoulders and took off my brassiere and hung it on the back of the chair and said, 'How's that, Aidan?'

I paint with my penis – didn't Renoir say that, Renoir of the plump, creamy-skinned ladies? Avec ma verge, feminine noun. Well, I thought to myself, let's see if we can wake Mr Phillips's verge out of its deep sleep. And I gave him my profile again, while the pigeons went on in the trees as if nothing were happening.

Whether it worked, whether the spectacle of me in the seminude rekindled anything in him, I cannot say. But I could feel the full weight of his gaze on me, on my breasts, and, frankly, it was good. I was forty then, I had two children behind me, they were not the breasts of a young woman, but it was good nevertheless, I thought so and think so still, in that place of withering away and dying. A blessing.

Then after a while, as the shadows in the garden lengthened and it grew cool, I made myself decent again. 'Goodbye, Aidan, God bless,' I said; and he wrote 'Thank you' on his pad and showed it to me, and that was that. I do not think he expected me to come back the next Saturday, and I did not. Whether he finished the painting by himself I don't know. Perhaps he destroyed it. He certainly did not show it to Mother.

Why am I telling you this story, Blanche? Because I connect it with the conversation you and I had at Marianhill about the Zulus and the Greeks and the true nature of the humanities. I do not want to give up on our dispute yet; I do not want to vacate the field.

The episode I am telling you about, the passage in Mr Phillips's living room, so minor in itself, has puzzled me for years; it is only now, after getting back from Africa, that I think I can explain it.

Of course there was an element of triumph in the way I behaved, an element of boasting, of which I am not proud: the potent woman teasing the waning man, showing her body off yet keeping him at a distance. Cock-teasing - do you remember cock-teasing from the old days?

But there was more to it than that. It was so out of character for me. Where did I get the idea, I kept wondering? Where did I learn that pose, gazing calmly into the distance with my robe hanging about my waist like a cloud and my divine body on show? From the Greeks, I now realize, Blanche: from the Greeks and from what generations of Renaissance painters made of the Greeks. As I sat there I was not myself, or not just myself. Through me a goddess was manifesting herself, Aphrodite or Hera or perhaps even Artemis. I was of the immortals.

And that is not the end of it. I used the word blessing a moment ago. Why? Because what was going on revolved around my breasts, that I was sure of, around breasts and breast-milk. Whatever else they did, those antique Grecian goddesses did not exude, whereas I was exuding, figuratively speaking: I was exuding into Mr Phillips's room, I felt it and I would bet he felt it too, long after I had taken my leave.

The Greeks do not exude. The one who exudes is Mary of Nazareth. Not the shy virgin of the Annunciation but the mother we see in Correggio, the one who delicately raises her nipple with her fingertips so that her baby can suck; who, secure in her virtue, boldly uncovers herself under the painter's gaze and thence under our gaze.

Imagine the scene in Correggio's studio that day, Blanche. With his brush the man points: 'Lift it up, so. No, not with the hand, just with two fingers.' He crosses the floor, shows her. 'So.' And the woman obeys, doing with her body as he commands. Other men watching all the while from the shadows: apprentices, fellow painters, visitors.

Who knows who she was, his model that day: a woman from the streets? the wife of a patron? The atmosphere in the studio electric, but with what? Erotic energy? The penises of all those men, their verges, tingling? Undoubtedly. Yet something else in the air too. Worship. The brush pauses as they worship the mystery that is manifested to them: from the body of the woman, life flowing in a stream.

Does Zululand have anything to match that moment, Blanche? I doubt it. Not that heady mix of the ecstatic and the aesthetic. It happens only once in the history of mankind, in Renaissance Italy, when immemorial Christian images and observances are invaded by the humanists' dream of antique Greece.

In all our talk about humanism and the humanities there was a word we both skirted: humanity. When Mary blessed among women smiles her remote angelic smile and tips her sweet pink nipple up before our gaze, when I, imitating her, uncover my breasts for old Mr Phillips, we perform acts of humanity. Acts like that are not available to animals, who cannot uncover themselves because they do not cover themselves. Nothing compels us to do it, Mary or me. But out of the overflow, the outflow of our human hearts we do it nevertheless: drop our robes, reveal ourselves, reveal the life and beauty we are blessed with.

Beauty. Surely from Zululand, where you have such an abundance of unclothed bodies to gaze on, you must concede, Blanche, that there is nothing more humanly beautiful than a woman's breasts. Nothing more humanly beautiful, nothing more humanly mysterious than why men should want to caress, over and over again, with paintbrush or chisel or hand, these oddly curved fatty sacs, and nothing more humanly endearing than our complicity (I mean the complicity of women) in their obsession.

The humanities teach us humanity. After the centuries-long Christian night, the humanities give us back our beauty, our human beauty. That was what you forgot to say. That is what the Greeks teach us, Blanche, the right Greeks. Think about it.

Your sister, Elizabeth

That is what she writes. What she does not write, what she has no intention of writing, is how the story proceeds, the story of Mr Phillips and their Saturday-afternoon sittings at the old folks' home.

For the story does not end as she said, with her covering herself decently and Mr Phillips writing his thank-you note and her quitting his rooms. No, the story picks up again a month later, when her mother mentions that Mr Phillips has been to hospital for another dose of radiation and has come back in a bad way, very low, very despondent. Why doesn't she look in on him, try to cheer him up?

She knocks at his door, waits a moment, enters.

No mistaking the signs. Not a spry old fellow any longer, just an old fellow, an old bag of bones waiting to be carted away. Flat on his back with his arms spread out, his hands slack, hands that have in the space of a month become so blue and knobbly that you wonder they were ever fit to hold a brush. Not sleeping, just lying, waiting. Listening too, no doubt, to the sounds inside, the sounds of the pain. (Let us not forget that, Blanche, she thinks to herself: let us not forget the pain. The terrors of death not enough: on top of them the pain, crescendo. As a way of putting to a close our visit to this world, what could he more ingeniously, more devilishly cruel?)

She stands at the old man's bedside; she takes his hand. Though there is nothing pleasant in folding that cold, blue hand in her own, she does it. Nothing pleasant in any of this. She holds the hand and squeezes it and says 'Aidan!' in her most affectionate voice and watches the tears well up, the old-folks' tears that do not count for much because they come too easily. Nothing more for her to say and nothing, certainly, for him to say through the hole in his throat, now decently covered with a wad of gauze. She stands there stroking his hand until Nurse Naidoo comes around with the tea trolley and the pills; then she helps him to sit up to drink (out of a cup with a spout, like a two-year-old, the humiliations have no limit).

The next Saturday she visits him again, and the next; it becomes a new routine. She holds his hand and tries to comfort him while marking with a cold eye the stages of his decline. The visits take place with a minimum of words. But there is one Saturday when, a little more chipper than usual, a little more spry, he pushes the pad towards her and she reads the message he has spelled out beforehand: 'A lovely bosom you have. I'll never forget. Thank you for everything, kind Elizabeth.'

She returns the pad to him. What is there to say? Take leave of what thou hast loved.

With crude, bony strength he tears the page from the pad, crumples it and drops it in the basket, and raises a finger to his lips as if to say, Our secret.

What the hell, she thinks to herself a second time. She crosses to the door and turns the latch. In the little alcove where he hangs his clothes she removes her dress, her brassiere. Then she crosses back to the bed, sits down side-on where he can get a good eyeful, and resumes the pose of the painting. A treat, she thinks: let's give the old boy a treat, let's brighten up his Saturday.

There are other things she thinks too, as she sits on Mr Phillips's bed in the cool of the afternoon (no longer summer now but autumn, late autumn), such cool that after a while she has even begun to shiver lightly. Consenting adults: that is one of the things she thinks. What consenting adults get up to behind closed doors is no one's business but their own.

That would be another good place to end the story. Whatever the true nature of this so-called treat, it does not need to be repeated. Next Saturday, if he is still alive, if she is still alive, she will come by and hold his hand again; but this must be the last of the posing, the last of the bosom-offering, the last of the blessing. After this the breasts must be closed up, maybe closed up for good. So it could end here, with this pose held for a good twenty minutes, she would estimate, despite the shivers. As a story, a recital, it could end here and still be decent enough to put in an envelope and send to Blanche without ruining whatever it was that she wanted to say about the Greeks.