The morning presented me with a fresh problem. I wanted to clean my teeth, but was a little suspicious of the delicate brown colour of the water leaking from the washbasin taps. I investigated the large flamboyant thermos flasks, but they were full of very hot water, for making tea. I poured some water from a thermos into a glass and left it to cool while I went to meet Mark and Chris Muir, our sound engineer, for a late breakfast.

Mark had already been trying to get through to Nanjing on the phone in an attempt to contact Professor Zhou, the baiji dolphin expert, and had come to the conclusion that it simply couldn't be done. We had two days to kill before our flight to Shanghai, so we might just as well be tourists for a bit.

I returned to my room to clean my teeth at last, to discover that the room maid had washed the glass I'd left out to cool, and refilled the thermoses with freshly boiled water.

I felt rather cast down by this. I tried pouring some water from one glass to another to cool it down, but even after doing this for a while the water was still hot, and the toothbrush wilted in my mouth.

I realised that I was going to have to come up with some serious strategic thinking if I was going to get to clean my teeth. I refilled the glass, carefully stuck it out of sight in the back of a cupboard, and then tried to get rid of one of the bottles of aftershave by hiding it under the bed.

We put on our sunglasses and cameras and went and spent the day looking at the Great Wall at Badaling, an hour or so outside Beijing. It looked to be remarkably freshly built for such an ancient monument, and probably the parts we saw had been.

I remembered once, in Japan, having been to see the Gold Pavilion Temple in Kyoto and being mildly surprised at quite how well it had weathered the passage of time since it was first built in the fourteenth century. I was told it hadn't weathered well at all, and had in fact been burnt to the ground twice in this century.

'So it isn't the original building? I had asked my Japanese guide.

'But yes, of course it is,' he insisted, rather surprised at my question.

'But it's been burnt down?

Yes.

'Twice.'

'Many times.'

'And rebuilt.'

'Of course. It is an important and historic building.'

'With completely new materials.'

'But of course. It was burnt down.'

'So how can it be the same building?'

'It is always the same building.'

I had to admit to myself that this was in fact a perfectly rational point of view, it merely started from an unexpected premise. The idea of the building, the intention of it, its design, are all immutable and are the essence of the building. The intention of the original builders is what survives. The wood of which the design is constructed decays and is replaced when necessary. To be overly concerned with the original materials, which are merely sentimental souvenirs of the past, is to fail to see the living building itself.

I couldn't feel entirely comfortable with this view, because it fought against my basic Western assumptions, but I had to see the point.

I don't know whether this principle lies beneath the rebuilding of the Great Wall, because I couldn't find anybody who understood the question. The rebuilt section was swarming with tourists and Coca-Cola booths and shops where you can buy Great Wall T-shirts and electric pandas, and this may also have had something to do with it.

We returned to our hotel.

The maid had found my hidden glass of water and washed it. She must have searched hard for it because she had also found the bottle of aftershave under the bed and had placed it neatly back on the table by the others.

`Why don't you just use the stuff? asked Mark.

`Because I've smelt them all and they're horrid.'

'You could give them to people for Christmas.'

`I don't want to carry them round the world till then.'

`Remind me again why you bought them.'

`I can't remember. Let's go to dinner.'

We went to a restaurant called Crispy Fried Duck for dinner, and walking back through the city centre afterwards we came to a square called Tiananmen.

I should explain that this was October 1988. I had never heard the name Tiananmen Square, and neither had most of the world

The square is huge. Standing in it at night you have very little idea of where its boundaries are, they fade into the distance. At one end is the gateway to the Forbidden City, the Tiananmen Gate, from which the great iconic portrait of Chairman Mao gazes out across the vastness of the square, out towards its furthest point where there stands the mausoleum in which his body lies in state.

In between these two, beneath his gaze, the mood was festive. Huge topiary bushes had been imported into the square carved into the figures of cartoon animals to celebrate the Olympics.

The square was not full or crowded - it would take many tens or even hundreds of thousands of people to achieve that - but it was busy. Families were out with their children (or more usually, with their single child). They walked around, chatting with friends, milling about easily and freely as if the square were their own garden, letting their children wander off and play with others without an apparent second thought. It would be hard to imagine anything of the kind in any of the great squares of Europe, and inconceivable in America.

In fact I cannot remember any time that I have felt so easy and relaxed in a busy public place, particularly at night. The background static of wary paranoia that you take with you as a matter of unconscious habit when you step out into the streets of Western cities made itself suddenly apparent by falling silent. It was a quite magical silence.

I have to say, though, that this was probably the only time we felt so easy in China, or indeed easy at all. For most of the time we found China baffling and exasperating and perpetually opaque; but that evening, in Tiananmen Square, was easy. So the greatest bewilderment of all came a few months later when Tiananmen Square underwent that brutal transformation that occurs in the public mind to the sites of all catastrophes: they become reference points in time instead of actual places. `Before Tiananmen Square' was when we were there. `After Tiananmen Square' was after the tanks rolled in.

We returned to the square early the following morning, while the air was still damp and misty, and joined the queues that line up round the square each day to file into the mausoleum and past the body of Chairman Mao, lying in state in a perspex box.

The length of the queue beggared belief. It zigzagged backwards and forwards across the square, each new fold of it looming up at you from out of the mist and disappearing into it again, rank after rank, line after line. People stood in line about three or four abreast, shuffled briskly forward across the square, made a turn and shuffled briskly back, again and again, all under the orders of officials who paraded up and down in flared trousers and yellow anoraks, barking through megaphones. The easy atmosphere of the previous evening had vanished in the dreary morning mist, and the square was degraded into a giant marshalling yard.

We joined the line after some hesitation, half-expecting that we might be there all day, but we were kept constantly on the move by the barking marshals, and even found that we were accelerating as we got closer to the front. Less than three hours after we had tagged on to the end of the line we were hurried into the red-pile-carpeted inner sanctum and ran past the tiny, plump, waxy body as respectfully as we could.

The queue which had been so tightly and rigorously controlled as it was lined up to be fed into the mausoleum, disintegrated amongst the souvenir stalls as it emerged from the other side. I imagined that from the air the building must resemble a giant mincing machine.