Christine kept going back, day after day. I don't know how long she spent trying to persuade Gladys, but the fact is that one day, Gladys left her chair and abandoned her unending wait for night to fall. Christine had succeeded. I asked Gladys what would have happened if Christine hadn't knocked on her door.

"I'd have still been sitting there, waiting to die."

And Christine?

"I knew that Gladys had many children. I heard that she was just sitting there in the darkness. I couldn't bear the thought of that. I thought that I might be able to talk her into making an effort to live longer."

Gladys also said: "I feel infinitely grateful to Christine. But for her, I'd have withered away. When she first came, I didn't want to listen to her. But she wouldn't give up. I thank her for that every morning when I wake up."

And Christine?

"I don't think I did anything out of the ordinary. It was just that I couldn't bear to walk past her house knowing that she was there, inside in the darkness, doing nothing, with no will to live. That was all. Nothing else."

In all I read some thirty memory books while I was in Uganda. Not all of them were complete, some had been interrupted by the death of the author and would never be more than fragments of stories. Some were written by people no longer with us, others had authors who were still alive.

Some were brief, laconic. That could be due to the style or the contents. There were some authors who knew practically nothing about their own ancestors, about the earlier generations of their families. They had left the "my family" pages blank. Other authors seemed to be overwhelmed by the feeling that they had "nothing to say". They thought they led humdrum lives. It had never occurred to them that they would leave any impression behind them apart from the houses they had built, the land they had cultivated, the children they had had. But even if some of the documents were thin, all of them were full of life, and often extremely expressive. Everything in them, whether written, drawn, pressed in the form of flowers or butterflies – everything was about life and death. Literally.

Most moving, of course, were the memory books written by sick parents of children who were still very small, in many cases infants. They would inherit these slim little books without having any memories whatsoever of the parent who had written this last will and testament bequeathing no money, no property. Nothing but a memory.

There were also memory books written by two parents together. They might not be married, but they have children together. Infidelity is a vague concept in cultures where polygamy has to do with traditions rather than a matter of morality. The infected parents sit together and write these memory books.

These suffering couples. It was as if they were sitting side by side, asking: Who are you? Who am I? Who are we? And so their memory books were created.

Needless to say, I also saw unwritten memory books. The pages remained blank. Not because the people concerned had no memories. Not because they had no desire, no intention of writing. They were blank memory books that bore witness to the overwhelming angst that induces paralysis in the face of disease, pain and death.

These empty memory books were almost always symptomatic of people who didn't dare start to write, as that was tantamount to accepting that death really was close at hand.

It is with Aids as it is with all other chronic diseases. Many of those infected will refuse to accept that they are ill until the bitter end. It starts much earlier, of course. When many people refuse to undergo tests. Some fall ill and will die with every symptom you can think of. But they insist that they are suffering from something else.

This disease is shameful, burdened with guilt. Whole villages, whole generations are riddled with guilt and shame in the shadow of Aids. Not everybody is affected in this way, not people like Gladys, Christine or Moses. But far too many are.

All those who refuse to accept that they are ill believe that they alone will survive. At least, as long as they refuse to start recording their memories in little exercise books made up of a few pages of grey paper.

One day my stay in Uganda comes to an end. In the evening I drive from Kampala to the airport in Entebbe. There is traffic chaos as usual, with frequent gridlocks: cars, overcrowded buses, lorries with lefhally packed loads. The only ones who get to where they want to go are those on cycles or mopeds, or on foot. It is Saturday evening, the jams are especially chronic. But eventually traffic starts moving again, and we get to the airport in time. The flight departs late at night and I head for Europe, and before long I shall be dreaming about the people in the coniferous forest.

Those faces projecting from the tree trunks, their frozen faces, their wordless horror. The coniferous forest crammed with the dying, and the already dead.

I must be honest. It was a relief to get away. So much death and suffering in a few intensive weeks is more than enough. I shall never forget the people I met. Nor shall I ever cease to be angry over the fact that so much of this suffering is unnecessary.

Christine again: the medication she needed cost twice her monthly wage as a teacher. She earned the equivalent of US$55 a month (£30). The drugs, in their simplest form, cost US$110. Approximately US$1300 (£720) per year. That's US$1300 for Christine, US$1300 for Moses, and another US$1300 for Gladys.

But they shouldn't really need to pay anything at all. When the history of this epidemic is eventually written, a chapter will be devoted to the gigantic pharmaceutical monopolies and the actions of their shareholders and executive boards during the years when Aids ravaged the world. No courts will be able to bring the owners of those companies to justice.

But the greed and inhumanity tells the story of our age. What we allowed to happen. We will never know how many people died before the drugs companies permitted or were forced to permit medicines to be manufactured in places and at prices that made the drugs accessible to the poorest people of the world.

The scale of this crisis is unique. The greed today concerning drug licensing, the ruthless exploitation of the weak economies, the increasing but nevertheless inadequate resources made available to combat Aids are another scandal. No wonder many Africans believe that the West has no objection to large numbers of poverty-stricken Africans being killed off so as to "ease the burden".

I think about this as I fly to London. It strikes me that these giant aircraft travelling through the night skies are the modern equivalent of sailing ships. In olden days they would ply the seas to Africa at a stately pace.

Nowadays, everything goes much faster. But the distances are no shorter. They are still vast. They are kept vast. They are not distances to be bridged. They are chasms to be left in place. Or patrolled.

The truth about Aids is of course a general truth about what the world is like today. In other words: what we allow the world to look like.