To a large extent, he was the master of his own time. Out of a sense of duty – and gratitude – he acceded to as many requests as he could from scientists, historians, writers and artists working in media that were often incomprehensible to him. He also had countless invitations from other citizens of the four Towers, virtually all of which he was compelled to turn down.

Most tempting – and most hard to resist – were those that came from the beautiful planet spread out below. 'Of course,' Professor Anderson had told him, 'you'd survive if you went down for short time with the right life-support system, but you wouldn't enjoy it. And it might weaken your neuromuscular system even further. It's never really recovered from that thousand-year sleep.'

His other guardian, Indra Wallace, protected him from unnecessary intrusions, and advised him which requests he should accept – and which he should politely refuse. By himself, he would never understand the socio-political structure of this incredibly complex culture, but he soon gathered that, although in theory all class distinctions had vanished, there were a few thousand super-citizens. George Orwell had been right; some would always be more equal than others.

There had been times when, conditioned by his twentyfirst-century experience, Poole had wondered who was paying for all this hospitality – would he one day be presented with the equivalent of an enormous hotel bill? But Indra had quickly reassured him: he was a unique and priceless museum exhibit, so would never have to worry about such mundane considerations. Anything he wanted – within reason – would be made available to him: Poole wondered what the limits were, never imagining that one day he would attempt to discover them.

All the most important things in life happen by accident, and he had set his wall display browser on random scan, silent, when a striking image caught his attention.