So Bao travelled, and talked, and wrote, and travelled again. For most of his career he worked for the League's Agency for Harmony with Nature, trying for several years to coordinate efforts in the Old World and the New to keep some of the greater mammals alive; many of them were going extinct, and without action they would lose most of them, in an anthropogenic extinction event to rival even the global crashes now being found in the fossil record.

He came back from these diplomatic missions to Pyinkayaing, after travelling in the big new airships that were a combination of blimp and flyer, hovercraft and catamaran, skating over the water or in the air depending on weather conditions and freight loads. He looked down on the world from his apartment, and saw the human relationship to nature drawn in the calligraphy of the water taxis' wakes, the airships' contrails, the great canyons formed by the city's skyscrapers. This was his world, changing every year; and when he visited Beijing and tried to remember his youth, or went to Kwinana in Aozhou, to see his son Zhao and family there, or when he tried to remember Pan Xichun – even when he visited Fangzhang once, the actual site of those years – he could scarcely call them to mind. Or, to be more precise – for he could remember a great many things that had happened – it was the feeling for these things that was gone away, leached out by the years. They if they had happened to someone else. As if they had been were as if previous incarnations.

It was someone else in the League offices who thought to invite Zhu Isao himself to Pyinkayaing, and teach a set of classes to the League workers and anyone else who cared to attend. Bao was surprised when he saw this notice; he had assumed that somewhere along the way Zhu must have died, it had been so long since they had all changed China together; and Zhu had been ancient then. But that turned out to have been a youthful mistake on Bao's part; Zhu was about ninety now, he was informed, meaning he had been only about seventy years old at that time. Bao had to laugh at his youthful miscalculation, so characteristic of the young. He signed up for the course with great anticipation.

Zhu Isao turned out to be a sprightly white haired old man, small but no smaller than he had been all those years before, with a lively curious look in his eye. He shook Bao's hand when Bao went up before the introductory lecture, and smiled a slight but friendly smile: 'I remember you,' he said. 'One of Kung Jianguo's officers, isn't that right?' And Bao gripped his hand hard, ducking his head in assent. He sat down feeling warm. The old man still walked with the ghost of a limp from that terrible day. But he had been happy to see Bao.

In his first lecture he outlined his plan for the course, which he hoped would be a series of conversations on history, discussing how it was constructed, and what it meant, and how they might use it to help them plot their course forwards through the next difficult decades, 'when we have to learn at last how to inhabit the Earth'.

Bao kept notes as he listened to the old man, tapping at his little hand lectern, as did many others in the class. Zhu explained that he hoped first to describe and discuss the various theories of history that had been proposed through the centuries, and then to analyse those theories, not only by testing them in the description of actual events, 'difficult since events as such are remembered for how well they prop up the various theories', but also for how the theories themselves were structured, and what sort of futures they implied, 'this being their chief use to us. I take it that what matters in a history is what there is in it we can put to use.'

So, over the next few months a pattern was set, and every third day the group would meet in a room high in one of the League buildings overlooking the Irrawaddy: a few score diplomats, local students, and younger historians from everywhere, many of whom had come to Pyinkayaing specifically for this class. All sat and listened to Zhu talk, and though Zhu kept encouraging them to enter the discussion and make of it a large conversation, they were mostly content to listen to him think aloud, only egging him on with their questions. 'Well, but I am here to listen too,' he would object, and then, when pressed to continue, would relent. 'I must be like Pao Ssu, I suppose, who used to say "I am a good listener, I listen by talking".'

So they made their way through discussions of the four civilizations theory, made famous by al Katalan; and al Lanzhou's collision of cultures theory, of progress by conflict ('clearly accurate in some sense, as there has been much conflict and much progress'); the somewhat similar conjunction theories, by which unnoticed conjunctions of developments, often in unrelated fields of endeavour, had great consequences. Zhu's many examples of this included one he presented with a small smile: the introduction of coffee and printing presses at around the same time in caliphate Iran, causing a great outpouring of literature. They discussed the theory of the eternal return, which combined Hindu cosmologies with the latest in physics to suggest that the universe was so vast and ancient that everything possible had not only happened, but had happened an infinite number of times ('limited usefulness to that one, except to explain the feeling you get that things have happened before'); and the other cyclical theories, often based on the cycle of the seasons, or the life of the body.

Then he mentioned 'dharma history' or 'Burmese history', meaning any history that believed there was progress towards some goal making itself manifest in the world, or in plans for the future; also 'Bodhisattva history', which suggested that there were enlightened cultures that had sprung ahead somehow, and then gone back to the rest and worked to bring them forwards – early China, Travancore, the Hodenosaunee, the Japanese diaspora, Iran – all these cultures had been proposed as possible examples of this pattern, 'though it seems to be a matter of individual or cultural judgment, which is less than useful to historians seeking a global pattern. Although it is a weak criticism to call them tautological, for the truth is every theory is tautological. Our reality itself is a tautology.'

Someone brought up the old question of whether the 'great man' or mass movements' were the principal force for change, but Zhu immediately dismissed this as a false problem. 'We are all great men, yes?'

'Maybe you are,' muttered the person sitting next to Bao.

What has mattered are the moments of exposure in every life, when habit is no longer enough, and choices have to be made. That's when everyone becomes the great man, for a moment; and the choices made in these moments, which come all too frequently, then combine to make history. In that sense I suppose I come down on the side of the masses, in that it has been a collective process, whatever else it is.

'Also, this formulation "the great man" of course should bring up the question of women; are they included in this description? Or should we describe history as being the story of women wresting back the political power that they lost with the introduction of agriculture and the creation of surplus wealth? Would the gradual and unfinished defeat of patriarchy be the larger story of history? Along with, perhaps, the gradual and uncertain defeat of infectious disease? So that we have been battling micro parasites and macro parasites, eh? The bugs and the patriarchs?'

He smiled at this, and went on to discuss the struggle against the Four Great Inequalities, and other concepts grown out of the work of Kang and al Lanzhou.

After that, Zhu took a few sessions to describe various 'phase change moments' in global history that he thought significant – the Japanese diaspora, the independence of the Hodenosaunee, the shift of trade from land to sea, the Samarqand Flowering, and so forth. He also spent quite a few sessions discussing the latest movement among historians and social scientists, which he called 'animal history', the study of humanity in biological terms, so that it became not a matter of religions and philosophies, but more a study of primates struggling for food and territory.